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pod::Prima::Widget(3) User Contributed Perl Documentationpod::Prima::Widget(3)

NAME
       Prima::Widget - window management

SYNOPSIS
	  # create a widget
	  my $widget = Prima::Widget-> new(
	      size    => [ 200,	200],
	      color   => cl::Green,
	      visible => 0,
	      onPaint => sub {
		 my ($self,$canvas) = @_;
		 $canvas-> clear;
		 $canvas-> text_out( "Hello world!", 10, 10);
	      },
	  );

	  # manipulate the widget
	  $widget-> origin( 10,	10);
	  $widget-> show;

DESCRIPTION
       Prima::Widget is	a descendant of	Prima::Component, a class, especially
       crafted to reflect and govern properties	of a system-dependent window,
       such as its position, hierarchy,	outlook	etc. Prima::Widget is mapped
       into the	screen space as	a rectangular area, with distinct boundaries,
       pointer and sometimes cursor, and a user-selectable input focus.

USAGE
       Prima::Widget class and its descendants are used	widely throughout the
       toolkit,	and, indeed provide almost all its user	interaction and	input-
       output.	The notification system, explained in Prima::Object, is
       employed	in Prima::Widget heavily, providing the	programmer with
       unified access to the system-generated events, that occur when the user
       moves windows, clicks the mouse,	types the keyboard, etc. Descendants
       of Prima::Widget	use the	internal, the direct method of overriding the
       notifications, whereas end programs tend	to use the toolkit widgets
       equipped	with anonymous subroutines ( see Prima::Object for the
       details).

       The class functionality is much more extensive comparing	to the other
       built-in	classes, and therefore the explanations	are grouped in several
       topics.

Creation and destruction
       The widget creation syntax is the same as for the other Prima objects:

	  Prima::Widget-> create(
	     name => 'Widget',
	     size => [ 20, 10],
	     onMouseClick => sub { print "click\n"; },
	     owner => $owner,
	  );

       In the real life, a widget must be almost always	explicitly told	about
       its owner. The owner object is either a Prima::Widget descendant, in
       which case the widget is	drawn inside its inferior, or the application
       object, and in the latter case a	widget becomes top-level. This is the
       reason why the "insert" syntax is much more often used, as it is	more
       illustrative and	is more	convenient for creating	several	widgets	in one
       call ( see Prima::Object	).

	  $owner-> insert( 'Prima::Widget',
	     name => 'Widget',
	     size => [ 20, 10],
	     onMouseClick => sub { print "click\n"; },
	  );

       These two examples produce identical results.

       As a descendant of Prima::Component, Prima::Widget sends	"Create"
       notification when created ( more	precisely, after its init stage	is
       finished. See Prima::Object for details). This notification is called
       and processed within "create()" call. In	addition, another notification
       "Setup" is sent after the widget	is created. This message is posted, so
       it is called within "create()" but processed in the application event
       loop. This means	that the execution time	of "Setup" is uncertain, as it
       is with all posted messages; its	delivery time is system-dependent, so
       its use must be considered with care.

       After a widget is created, it is	usually	asked to render	its content,
       provided	that the widget	is visible. This request is delivered by means
       of "Paint" notification.

       When the	life time of a widget is over, its method "destroy()" is
       called, often implicitly. If a widget gets destroyed because its	owner
       also does, it is	guaranteed that	the children widgets will be destroyed
       first, and the owner afterwards.	In such	situation, widget can operate
       with a limited functionality both on itself and its owners ( see
       Prima::Object, Creation section ).

Graphic	content
       A widget	can use	two different ways for representing its	graphic
       content to the user. The	first method is	event-driven, when the "Paint"
       notification arrives, notifying the widget that it must re-paint
       itself.	The second is the 'direct' method, when	the widget generates
       graphic output unconditionally.

   Event-driven	rendering
       A notification responsible for widget repainting	is "Paint".  It
       provides	a single ( besides the widget itself ) parameter, an object,
       where the drawing is performed. In an event-driven call,	it is always
       equals to the widget. However, if a custom mechanism should be used
       that directly calls, for	example,

	  $widget-> notify('Paint', $some_other_widget);

       for whatever purpose, it	is recommended ( not required, though ), to
       use this	parameter, not the widget itself for painting and drawing
       calls.

       The example of "Paint" callback is quite	simple:

	  Prima::Widget-> create(
	      ...
	      onPaint => sub {
		 my ( $self, $canvas) =	@_;
		 $canvas-> clear;
		 $canvas-> text_out("Clicked $self->{clicked} times", 10, 10);
	      },
	      onMouseClick => sub {
		 $_[0]-> {clicked}++;
		 $_[0]-> repaint;
	      },
	  );

       The example uses	several	important features of the event-driven
       mechanism. First, no "begin_paint()"/"end_paint()" brackets are used
       within the callback. These are called implicitly.  Second, when the
       custom refresh of the widget's graphic content is needed, no code like
       "notify(q(Paint))" is used - "repaint()"	method is used instead.	 It
       must be noted, that the actual execution	of "Paint" callbacks might or
       might not occur inside the "repaint()" call. This behavior is governed
       by the "::syncPaint" property.  "repaint()" marks the whole widget's
       area to be refreshed, or	invalidates the	area. For the finer gradation
       of the area that	should be repainted, "invalidate_rect()" and
       "validate_rect()" pair of functions is used. Thus,

	 $x-> repaint()

       code is a mere alias to

	 $x-> invalidate_rect( 0, 0, $x-> size);

       call. It	must be	realized, that the area, passed	to "invalidate_rect()"
       only in its ideal ( but a quite often ) execution case will be
       pertained as a clipping rectangle when a	widget executes	its "Paint"
       notification.  The user and system interactions can result in
       exposition of other parts of a widget ( like, moving windows over a
       widget ), and the resulting clipping rectangle can be different from
       the one that was	passed to "invalidate_rect()". Moreover, the clipping
       rectangle can become empty as the result	of these influences, and the
       notification will not be	called at all.

       Invalid rectangle is presented differently inside and outside the
       drawing mode. The first,	returned by "::clipRect", employs inclusive-
       inclusive coordinates, whereas "invalidate_rect()", "validate_rect()"
       and "get_invalid_rect()"	- inclusive-exclusive coordinates. The ideal
       case exemplifies	the above said:

	  $x-> onPaint(	sub {
	     my	@c = $_[0]-> clipRect;
	     print "clip rect:@c\n";
	  });
	  $x-> invalidate_rect(	10, 10,	20, 20);
	  ...
	  clip rect: 10	10 19 19

       As noted	above, "::clipRect" property is	set to the clipping rectangle
       of the widget area that is needed to be refreshed, and an event handler
       code can	take advantage of this information, increasing the efficiency
       of the painting procedure.

       Further assignments of "::clipRect" property do not make	possible over-
       painting	on the screen area that	lies outside the original clipping
       region. This is also valid for all paint	operations, however since the
       original	clipping rectangle is the full area of a canvas, this rule is
       implicit	and unnecessary, because whatever large	the clipping rectangle
       is, drawing and painting	cannot be performed outside the	physical
       boundaries of the canvas.

   Direct rendering
       The direct rendering, contrary to the event-driven, is initiated	by the
       program,	not by the system. If a	programmer wishes to paint over	a
       widget immediately, then	"begin_paint()"	is called, and,	if successful,
       the part	of the screen occupied by the widget is	accessible to the
       drawing and painting routines.

       This method is useful, for example, for graphic demonstration programs,
       that draw continuously without any input.  Another field	is the screen
       drawing,	which is performed with	Prima::Application class, that does
       not have	"Paint"	notification. Application's graphic canvas represents
       the whole screen, allowing over-drawing the graphic content of other
       programs.

       The event-driven	rendering method adds implicit
       "begin_paint()"/"end_paint()" brackets (	plus some system-dependent
       actions ) and is	a convenience version of the direct rendering.
       Sometimes, however, the changes needed to be made to a widget's graphic
       context are so insignificant, so	the direct rendering method is
       preferable, because of the cleaner and terser code. As an example might
       serve a simple progress bar, that draws a simple	colored	bar.  The
       event-driven code would be ( in short, omitting many details ) as such:

	  $bar = Widget-> create(
	    width => 100,
	    onPaint => sub {
	       my ( $self, $canvas) = @_;
	       $canvas-> color(	cl::Blue);
	       $canvas-> bar( 0, 0, $self-> {progress},	$self->	height);
	       $canvas-> color(	cl::Back);
	       $canvas-> bar( $self-> {progress}, 0, $self-> size);
	    },
	  );
	  ...
	  $bar-> {progress} += 10;
	  $bar-> repaint;
	  # or,	more efficiently, ( but	clumsier )
	  # $bar-> invalidate_rect( $bar->{progress}-10, 0,
	  #		    $bar->{progress}, $bar-> height);

       And the direct driven:

	  $bar = Widget-> create( width	=> 100 );
	  ...
	  $bar-> begin_paint;
	  $bar-> color(	cl::Blue);
	  $bar-> bar( $progress, 0, $progress +	10, $bar-> height);
	  $bar-> end_paint;
	  $progress += 10;

       The pros	and contras are	obvious: the event-driven rendered widget
       correctly represents the	status after an	eventual repaint, for example
       when the	user sweeps a window over the progress bar widget. The direct
       method cannot be	that smart, but	if the status bar is an	insignificant
       part of the program, the	trade-off of the functionality in favor	to the
       code simplicity might be	preferred.

       Both methods can	be effectively disabled	using the paint	locking
       mechanism. The "lock()" and "unlock()" methods can be called several
       times, stacking the requests. This feature is useful because many
       properties implicitly call "repaint()", and if several of these
       properties activate in a	row, the unnecessary redrawing of the widget
       can be avoided.	The drawback is	that the last "unlock()" call triggers
       "repaint()" unconditionally.

Geometry
   Basic properties
       A widget	always has its position	and size determined, even if it	is not
       visible on the screen. Prima::Widget provides several properties	with
       overlapping functionality, that govern the geometry of a	widget.	The
       base properties are "::origin" and "::size", and	the derived are
       "::left", "::bottom", "::right",	"::top", "::width", "::height" and
       "::rect". "::origin" and	"::size" operate with two integers, "::rect"
       with four, others with one integer value.

       As the Prima toolkit coordinate space begins in the lower bottom
       corner, the combination of "::left" and "::bottom" is same as
       "::origin", and combination of "::left",	"::bottom", "::right" and
       "::top" - same as "::rect".

       When a widget is	moved or resized, correspondingly two notifications
       occur: "Move" and "Size". The parameters	to both	are old	and new
       position	and size. The notifications occur irrespectable	to whether the
       geometry	change was issued by the program itself	or by the user.

   Implicit size regulations
       Concerning the size of a	widget,	two additional two-integer properties
       exist, "::sizeMin" and "::sizeMax", that	constrain the extension	of a
       widget in their boundaries. The direct call that	assigns	values to the
       size properties that lie	outside	"::sizeMin" and	"::sizeMax"
       boundaries, will	fail - the widget extension will be adjusted to	the
       boundary	values,	not to the specified ones.

       Change to widget's position and size can	occur not only by an explicit
       call to one of the geometry properties. The toolkit contains implicit
       rules, that can move and	resize a widget	corresponding to the flags,
       given to	the "::growMode" property. The exact meaning of	the "gm::XXX"
       flags is	not given here ( see description to "::growMode" in API
       section ), but in short,	it is possible with simple means to maintain
       widget's	size and position regarding its	owner, when the	latter is
       resized.	By default, and	the default behavior corresponds to
       "::growMode" 0, widget does not change neither its size nor position
       when its	owner is resized. It stays always in 'the left bottom corner'.
       When, for example, a widget is expected to stay in 'the right bottom
       corner',	or 'the	left top corner', the "gm::GrowLoX" and	"gm::GrowLoY"
       values must be used, correspondingly.  When a widget is expected	to
       cover, for example, its owner's lower part and change its width in
       accord with the owner's,	( a horizontal scroll bar in an	editor window
       is the example),	the "gm::GrowHiX" value	must be	used.

       When this implicit size change does occur, the "::sizeMin" and
       "::sizeMax" do take their part as well -	they still do not allow	the
       widget's	size to	exceed their boundaries. However, this algorithm has a
       problem,	that is	illustrated by the following setup. Imagine a widget
       with size-dependent "::growMode"	( with "gm::GrowHiX" or	"gm::GrowHiY"
       bits set	) that must maintain certain relation between the owner's size
       and its own. If the implicit size change	would depend on	the actual
       widget size, derived as a result	from the previous implicit size
       action, then its	size (and probably position) will be incorrect after
       an attempt is made to change the	widget's size to values	outside	the
       size boundaries.

       Example:	child widget has width 100, growMode set to "gm::GrowHiX" and
       sizeMin set to (95, 95).	Its owner has width 200.  If the owner widget
       changes gradually its width from	200 to 190 and then back, the
       following width table emerges:

			   Owner	Child
	 Initial state	    200		  100
	 Shrink		    195	  -5	   95
	 Shrink		    190	  -5	   95 -	as it can not be less than 95.
	 Grow		    195	  +5	  100
	 Grow		    200	  +5	  105

       That effect would exist if the differential-size	algorithm would	be
       implemented, - the owner	changes	width by 5, and	the child does the
       same.  The situation is fixed by	introducing the	virtual	size term.
       The "::size" property is	derived	from virtual size, and as "::size"
       cannot exceed the size boundaries, virtual size can.  It	can even
       accept the negative values. With	this intermediate stage	added, the
       correct picture occurs:

			   Owner	Child's	      Child's
					virtual	width  width
	 Initial state	    200		  100		100
	 Shrink		    195	  -5	   95		 95
	 Shrink		    190	  -5	   90		 95
	 Grow		    195	  +5	   95		 95
	 Grow		    200	  +5	  100		100

   Geometry managers
       The concept of geometry managers	is imported from Tk, which in turn is
       a port of Tcl-Tk. The idea behind it is that a widget size and position
       is governed by one of the managers, which operate depending on the
       specific	options	given to the widget. The selection is operated by
       "::geometry" property, and is one of "gt::XXX" constants. The native (
       and the default ) geometry manager is the described above grow-mode
       algorithm ( "gt::GrowMode" ). The currently implemented Tk managers are
       packer (	"gt::Pack" ) and placer	( "gt::Place").	 Each has its own set
       of options and methods, and their manuals are provided separately in
       Prima::Widget::pack and Prima::Widget::place ( the manpages are also
       imported	from Tk	).

       Another concept that comes along	with geometry managers is the
       'geometry request size'.	 It is realized	as a two-integer property
       "::geomSize", which reflects the	size deduced by	some intrinsic widget
       knowledge. The idea is that "::geomSize"	it is merely a request to a
       geometry	manager, whereas the latter changes "::size" accordingly. For
       example,	a button might set its 'intrinsic' width in accord with	the
       width of	text string displayed in it. If	the default width for such a
       button is not overridden, it is assigned	with such a width. By default,
       under "gt::GrowMode" geometry manager, setting "::geomSize" ( and its
       two semi-alias properties "::geomWidth" and "::geomHeight" ) also
       changes the actual widget size.Moreover,	when the size is passed	to the
       Widget initialization code, "::size" properties are used	to initialize
       "::geomSize".  Such design minimizes the	confusion between the two
       properties, and also minimizes the direct usage of "::geomSize",
       limiting	it for selecting advisory size in widget internal code.

       The geometry request size is useless under "gt::GrowMode" geometry
       manager,	but Tk managers	use it extensively.

   Relative coordinates
       Another geometry	issue, or rather a programming technique must be
       mentioned - the relative	coordinates. It	is the well-known problem,
       when a dialog window, developed with one	font looks garbled on another
       system with another font. The relative coordinates solve	that problem;
       the solution is to use the "::designScale" two-integer property,	the
       width and height	of the font, that was used when	the dialog window was
       designed. With this property supplied, the position and size supplied
       when a widget is	actually created, are transformed in proportion
       between the designed and	the actual font	metrics.

       The relative coordinates	can be used only when passing the geometry
       properties values, and only before the creation stage, before a widget
       is created, because the scaling calculations perform in
       Prima::Widget::"profile_check_in()" method.

       In order	to employ the relative coordinates scheme, the owner ( or the
       dialog )	widget must set	its "::designScale" to the font	metrics	and
       "::scaleChildren" property to 1.	 Widgets, created with owner that
       meets these requirements, participate in	the relative coordinates
       scheme. If a widget must	be excluded from the relative geometry
       applications, either the	owner's	property "::scaleChildren" must	be set
       to 0, or	the widget's "::designScale" must be set to "undef".  As the
       default "::designScale" value is	"undef", no default implicit relative
       geometry	schemes	are applied.

       The "::designScale" property is auto-inherited; its value is copied to
       the children widgets, unless the	explicit "::designScale" was given
       during the widget's creation. This is used when such a child widget
       serves as an owner for some other grand-children	widgets; the
       inheritance scheme allows the grand- ( grand- etc ) children to
       participate in the relative geometry scheme.

       Note: it	is advised to test such	applications with the Prima::Stress
       module, which assigns a random font as the default, so the testing
       phase does not involve tweaking of the system settings.

Z-order
       In case when two	widgets	overlap, one of	these is drawn in full,
       whereas the another only	partly.	Prima::Widget provides management of
       the Z-axis ordering, but	since Z-ordering paradigm can hardly be	fit
       into the	properties scheme, the toolkit uses methods instead.

       A widget	can use	four query methods: "first()", "last()", "next()", and
       "prev()". These return, correspondingly,	the first and the last widgets
       in Z-order stack, and the direct	neighbors of a widget (	$widget->
       next-> prev always equals to the	$widget	itself,	given that $widget->
       next exists ).

       The last	widget is the topmost one, the one that	is drawn fully.	 The
       first is	the most obscured one, given that all the widgets overlap.

       Z-order can also	be changed at runtime (	but not	during widget's
       creation). There	are three methods: "bring_to_front()", that sets the
       widget last in the order, making	it topmost, "send_to_back()", that
       does the	reverse, and "insert_behind()",	that sets a widget behind the
       another widget, passed as an argument.

       Changes to Z-order trigger "ZOrderChanged" notification.

Parent-child relationship
       By default, if a	widget is a child to a widget or a window, it
       maintains two features: it is clipped by	its owner's boundaries and is
       moved together as the owner widget moves, i.e. a	child is inferior to
       its parent. However, a widget without a parent still does have a	valid
       owner.  Instead of implementing parent property,	the "::clipOwner"
       property	was devised. It	is 1 by	default, and if	it is 1, then owner of
       a widget	is its parent, at the same time. However, when it is 0,	many
       things change. The widget is neither clipped nor	moved together with
       its parent. The widget become parentless, or, more strictly speaking,
       the screen becomes its parent. Moreover,	the widget's origin offset is
       calculated then not from	the owner's coordinates	but from the screen,
       and mouse events	in the widget do not transgress	implicitly to the
       owner's top-level window	eventual decorations.

       The same	results	are produced if	a widget is inserted in	the
       application object, which does not have screen visualization.  A	widget
       that belongs to the application object, can not reset its "::clipOwner"
       value to	1.

       The "::clipOwner" property opens	a possibility for the toolkit widgets
       to live inside other programs' windows. If the "::parentHandle" is
       changed from its	default	"undef"	value to a valid system	window handle,
       the widget becomes child	to this	window,	which can belong to any
       application residing on the same	display. This option is	dangerous,
       however:	normally widgets never get destroyed by	no reason. A top-level
       window is never destroyed before	its "Close" notification grants	the
       destruction.  The case with "::parentHandle" is special,	because	a
       widget, inserted	into an	alien application, must	be prepared to be
       destroyed at any	moment.	It is recommended to use prior knowledge about
       such the	application, and, even better, use one or another inter-
       process communication scheme to interact	with it.

       A widget	does not need to undertake anything special to become an
       'owner'.	 Any widget, that was set in "::owner" property	on any other
       widget, becomes an owner	automatically. Its "get_widgets()" method
       returns non-empty widget	list. "get_widgets()" serves same purpose as
       Prima::Component::"get_components()", but returns only Prima::Widget
       descendants.

       A widget	can change its owner at	any moment. The	"::owner" property is
       both readable and writable, and if a widget is visible during the owner
       change, it is immediately appeared under	different coordinates and
       different clipping condition after the property change, given that its
       "::clipOwner" is	set to 1.

Visibility
       A widget	is created visible by default. Visible means that it is	shown
       on the screen if	it is not shadowed by other widgets or windows.	The
       visibility is governed by the "::visible" property, and its two
       convenience aliases, "show()" and "hide()".

       When a widget is	invisible, its geometry	is not discarded; the widget
       pertains	its position and size, and is subject to all previously
       discussed implicit sizing issues. When change to	"::visible" property
       is made,	the screen is not updated immediately, but in the next event
       loop invocation,	because	uncovering of the underlying area of a hidden
       widget, and repainting of a new-shown widget both depend	onto the
       event-driven rendering functionality. If	the graphic content must be
       updated,	"update_view()"	must be	called,	but there's a problem. It is
       obvious that if a widget	is shown, the only content to be updated is
       its own.	When a widget becomes hidden, it may uncover more than one
       widget, depending on the	geometry, so it	is unclear what	widgets	must
       be updated.  For	the practical reasons, it is enough to get one event
       loop passed, by calling "yield()" method	of the $::application object.
       The other notifications may pass	here as	well, however.

       There are other kinds of	visibility. A widget might be visible, but one
       of its owners might not.	Or, a widget and its owners might be visible,
       but they	might be over-shadowed by the other windows. These conditions
       are returned by "showing()" and "exposed()" functions, correspondinly.
       These return boolean values corresponding to the	condition described.
       So, if a	widget is 'exposed', it	is 'showing' and 'visible';
       "exposed()" returns always 0 if a widget	is either not 'showing'	or not
       'visible'. If a widget is 'showing', then it is always 'visible'.
       "showing()" returns always 0 if a widget	is invisible.

       Visibility changes trigger "Hide" and "Show" notifications.

Focus
       One of the key points of	any GUI	is that	only one window	at a time can
       possess a focus.	The widget is focused, if the user's keyboard input is
       directed	to it. The toolkit adds	another	layer in the focusing scheme,
       as often	window managers	do, highlighting the decorations of a top-
       level window over a window with the input focus.

       Prima::Widget property "::focused" governs the focused state of a
       widget. It is sometimes too powerful to be used.	Its more often
       substitutes, "::selected" and "::current" properties provide more
       respect to widget hierarchy.

       "::selected" property sets focus	to a widget if it is allowed to	be
       focused,	by the usage of	the "::selectable" property. With this
       granted,	the focus is passed to the widget or to	the one	of its (
       grand-) children.  So to	say, when 'selecting' a	window with a text
       field by	clicking on a window, one does not expect the window itself to
       be focused, but the text	field. To achieve this goal and	reduce
       unnecessary coding, the "::current" property is introduced. With	all
       equal conditions, a widget that is 'current' gets precedence in getting
       selected	over widgets that are not 'current'.

       De-selecting, in	its turn, leaves the system in such a state when no
       window has input	focus. There are two convenience shortcuts "select()"
       and "deselect()"	defined, aliased to selected(1)	and selected(0),
       correspondingly.

       As within the GUI space,	there can be only one 'focused'	widget,	so
       within the single widget	space, there can be only one 'current' widget.
       A widget	can be marked as a current by calling "::current" ( or,
       identically, "::currentWidget" on the owner widget ).  The
       reassignments are performed automatically when a	widget is focused.
       The reverse is also true: if a widget is	explicitly marked as
       'current', and belongs to the widget tree with the focus	in one of its
       widgets,	then the focus passed to the 'current' widget, or down to its
       hierarchy if it is not selectable.

       These relations between current widget pointer and focus	allow the
       toolkit easily implement	the focusing hierarchy.	The focused widget is
       always on the top of the	chain of its owner widgets, each of whose is a
       'current' widget. If, for example, a window that	contains a widget that
       contains	a focused button, become un-focused, and then user selects the
       window again, then the button will become focused automatically.

       Changes to focus	produce	"Enter"	and "Leave" notifications.

       Below discussed mouse- and keyboard- driven focusing schemes.  Note
       that all	of these work via "::selected",	and do not focus the widgets
       with "::selectable" property set	to 0.

   Mouse-aided focusing
       Typically, when the user	clicks the left	mouse button on	a widget, the
       latter becomes focused.	One can	note that not all widgets become
       focused after the mouse click - scroll bars are the examples. Another
       kind of behavior	is the described above window with the text field -
       clicking	mouse on a window focuses a text field.

       Prima::Widget has the "::selectingButtons" property, a combination of
       mb::XXX ( mouse buttons ) flags.	If the bits corresponding to the
       buttons are set,	then click of this button will automatically call
       ::selected(1) ( not ::focused(1)	).

       Another boolean property, "::firstClick"	determines the behavior	when
       the mouse button	action is up to	focus a	widget,	but the	widget's top-
       level window is not active. The default value of	"::firstClick" is 1,
       but if set otherwise, the user must click twice to a widget to get it
       focused.	The property does not influence	anything if the	top-level
       window was already active when the click	event occured.

       Due to different	GUI designs, it	is hardly possibly to force selection
       of one top-level	window when the	click was on the another.  The window
       manager or the OS can interfere,	although this does not always happen,
       and produces different results on different platforms. Since the
       primary goal of the toolkit is portability, such	functionality must be
       considered with care.  Moreover,	when the user selects a	window by
       clicking	not on the toolkit-created widgets, but	on the top-level
       window decorations, it is not possible to discern the case from any
       other kind of focusing.

   Keyboard focusing
       The native way to navigate between the toolkit widgets are tab- and
       arrow- navigation. The tab ( and	its reverse, shift-tab ) key
       combinations circulate the focus	between	the widgets in same top-level
       group ( but not inside the same owner widget group ). The arrow keys,
       if the focused widget is	not interested in these	keystrokes, move the
       focus in	the specified direction, if it is possible. The	methods	that
       provide the navigations are available and called	"next_tab()" and
       "next_positional()", correspondingly ( see API for the details).

       When "next_positional()"	operates with the geometry of the widgets,
       "next_tab()" uses the "::tabStop" and "::tabOrder" properties.
       "::tabStop", the	boolean	property, set to 1 by default, tells if	a
       widget is willing to participate	in tab-aided focus circulation.	If it
       doesn't,	"next_tab()" never uses	it in its iterations.  "::tabOrder"
       value is	an integer, unique within the sibling widgets (	sharing	same
       owner ) list, and is used as simple tag when the	next tab-focus
       candidate is picked up. The default "::tabOrder"	value is -1, which
       changes automatically after widget creation to a	unique value.

User input
       The toolkit responds to the two basic means of the user input - the
       keyboard	and the	mouse. Below described three aspects of	the input
       handling	- the event-driven, the	polling	and the	simulated input
       issues. The event-driven	input is the more or less natural way of
       communicating with the user, so when the	user presses the key or	moves
       the mouse, a system event occurs	and triggers the notification in one
       or more widgets.	Polling	methods	provide	the immediate state of the
       input devices; the polling is rarely employed, primarily	because	of its
       limited usability, and because the information it provides is passed to
       the notification	callbacks anyway.  The simulated input is little more
       than "notify()" call with specifically crafted parameters. It interacts
       with the	system,	so the emulation can gain the higher level of
       similarity to the user actions. The simulated input functions allow the
       notifications to	be called right	away, or post it, delaying the
       notification until the next event loop invocation.

   Keyboard
       Event-driven
	   Keyboard input generates several notifications, where the most
	   important are "KeyDown" and "KeyUp".	Both have almost the same list
	   of parameters ( see API ), that contain the key code, its modifiers
	   ( if	any ) that were	pressed	and an eventual	character code.	The
	   algorithms that extract the meaning of the key, for example,
	   discretion between character	and functional keys etc	are not
	   described here. The reader is advised to look at Prima::KeySelector
	   module, which provides convenience functions	for keyboard input
	   values transformations, and to the Prima::Edit and Prima::InputLine
	   modules, the	classes	that use extensively the keyboard input. But
	   in short, the key code is one of the	"kb::XXX" ( like, kb::F10,
	   kb::Esc ) constants,	and the	modifier value is a combination	of the
	   "km::XXX" ( km::Ctrl, km::Shift) constants. The notable exception
	   is kb::None value, which hints that the character code is of	value.
	   Some	other "kb::XXX"-marked keys have the character code as well,
	   and it is up	to a programmer	how to treat these combinations. It is
	   advised, however, to	look at	the key	code first, and	then to	the
	   character code.

	   "KeyDown" event has also the	repeat integer parameter, that shows
	   the repetitive count	how many times the key was pressed.  Usually
	   it is 1, but	if a widget was	not able to get	its portion of events
	   between the key presses, its	value can be higher.  If a code
	   doesn't check for this parameter, some keyboard input may be	lost.
	   If the code will be too much	complicated by introducing the repeat-
	   value, one may consider setting the "::briefKeys" property to 0.
	   "::briefKeys", the boolean property,	is 1 by	default.  If set to 0,
	   it guarantees that the repeat value will always be 1, but with the
	   price of certain under-optimization.	If the core "KeyDown"
	   processing code sees	repeat value greater than 1, it	simply calls
	   the notification again.

	   Along with these two	notifications, the "TranslateAccel" event is
	   generated after "KeyDown", if the focused widget is not interested
	   in the key event. Its usage covers the needs	of the other widgets
	   that	are willing to read the	user input, even being out of focus.
	   A notable example can be a button with a hot	key, that reacts on
	   the key press when the focus	is elsewhere within its	top-level
	   window.  "TranslateAccel" has same parameters as "KeyDown", except
	   the REPEAT parameter.

	   Such	out-of-focus input is also used	with built-in menu keys
	   translations.  If a descendant of Prima::AbstractMenu is in the
	   reach of the	widget tree hierarchy, then it is checked whether it
	   contains some hot keys that match the user input. See Prima::Menu
	   for the details. In particular, Prima::Widget has "::accelTable"
	   property, a mere slot for an	object that contains a table of	hot
	   keys	mappings to custom subroutines.

       Polling
	   The polling function	for the	keyboard is limited to the modifier
	   keys	only. "get_shift_state()" method returns the press state of
	   the modifier	keys, a	combination of "km::XXX" constants.

       Simulated input
	   There are two methods, corresponding	to the major notifications -
	   "key_up()" and "key_down()",	that accept the	same parameters	as the
	   "KeyUp" and "KeyDown" notifications do, plus	the POST boolean flag.
	   See "API" for details.

	   These methods are convenience wrappers for "key_event()" method,
	   which is never used directly.

   Mouse
       Event-driven
	   Mouse notifications are send	in response when the user moves	the
	   mouse, or presses and releases mouse	buttons.  The notifications
	   are logically grouped in two	sets, the first	contains "MouseDown",
	   "MouseUp", "MouseClick", and	"MouseWheel", and the second -
	   "MouseMove",	"MouseEnter", end "MouseLeave".

	   The first set deals with button actions. Pressing, de-pressing,
	   clicking ( and double-clicking ), the turn of mouse wheel
	   correspond to the four notifications. The notifications are sent
	   together with the mouse pointer coordinates,	the button that	was
	   touched, and	the eventual modifier keys that	were pressed.  In
	   addition, "MouseClick" provides the boolean flag if the click was
	   single or double, and "MouseWheel" the wheel	turn amount. These
	   notifications occur when the	mouse event occurs within the
	   geometrical bounds of a widget, with	one notable exception, when a
	   widget is in	capture	mode.  If the "::capture" is set to 1, then
	   these events	are sent to the	widget even if the mouse pointer is
	   outside, and	not sent to the	widgets	and windows that reside	under
	   the pointer.

	   The second set deals	with the pointer movements. When the pointer
	   passes over a widget, it receives first "MouseEnter", then series
	   of "MouseMove", and finally "MouseLeave". "MouseMove" and
	   "MouseEnter"	notifications provide X,Y-coordinates and modificator
	   keys; "MouseLeave" passes no	parameters.

       Polling
	   The mouse input polling procedures are "get_mouse_state()" method,
	   that	returns	combination of "mb::XXX" constants, and	the
	   "::pointerPos" two-integer property that reports the	current
	   position of the mouse pointer.

       Simulated input
	   There are five methods, corresponding to the	mouse events -
	   "mouse_up()", "mouse_down()", "mouse_click()", "mouse_wheel()" and
	   "mouse_move()", that	accept the same	parameters as their event
	   counterparts	do, plus the POST boolean flag.	See "API" for details.

	   These methods are convenience wrappers for "mouse_event()" method,
	   which is never used directly.

Color schemes
       Prima::Drawable deals only with such color values, that can be
       unambiguously decomposed	to their red, green and	blue components.
       Prima::Widget extends the range of the values acceptable	by its color
       properties, introducing the color schemes.  The color can be set
       indirectly, without prior knowledge of what is its RGB value. There are
       several constants defined in "cl::" name	space, that correspond to the
       default values of different color properties of a widget.

       Prima::Widget revises the usage of "::color" and	"::backColor", the
       properties inherited from Prima::Drawable. Their	values are widget's
       'foreground' and	'background' colors, in	addition to their function as
       template	values.	Moreover, their	dynamic	change induces the repainting
       of a widget, and	they can be inherited from the owner. The inheritance
       is governed by properties "::ownerColor"	and "::ownerBackColor".	While
       these are true, changes to owner	"::color" or "::backColor" copied
       automatically to	a widget. Once the widget's "::color" or "::backColor"
       are explicitly set, the owner link breaks automatically by setting
       "::ownerColor" or "::ownerBackColor" to 0.

       In addition to these two	color properties, Prima::Widget	introduces six
       others.	These are "::disabledColor", "::disabledBackColor",
       "::hiliteColor",	"::hiliteBackColor", "::light3DColor", and
       "::dark3DColor".	 The 'disabled'	color pair contains the	values that
       are expected to be used as foreground and background when a widget is
       in the disabled state ( see API,	"::enabled" property ).	The 'hilite'
       values serve as the colors for representation of	selection inside a
       widget. Selection may be	of any kind, and some widgets do not provide
       any. But	for those that do, the 'hilite'	color values provide distinct
       alternative colors. Examples are	selections in the text widgets,	or in
       the list	boxes. The last	pair, "::light3DColor" and "::dark3DColor" is
       used for	drawing	3D-looking outlines of a widget. The purpose of	all
       these properties	is the adequate	usage of the color settings, selected
       by the user using system-specific tools,	so the program written with
       the toolkit would look not such different, and more or less conformant
       to the user's color preferences.

       The additional "cl::" constants,	mentioned above, represent these eight
       color properties. These named correspondingly, cl::NormalText,
       cl::Normal, cl::HiliteText, cl::Hilite, cl::DisabledText, cl::Disabled,
       cl::Light3DColor	and cl::Dark3DColor. cl::NormalText is alias to
       cl::Fore, and cl::Normal	- to cl::Back. Another constant	set, "ci::"
       can be used with	the "::colorIndex" property, a multiplexer for all
       eight color properties. "ci::" constants	mimic their non-RGB "cl::"
       counterparts, so	the call "hiliteBackColor(cl::Red)" is equal to
       "colorIndex(ci::Hilite, cl::Red)".

       Mapping from these constants to the RGB color representation is used
       with "map_color()" method. These	"cl::" constants alone are sufficient
       for acquiring the default values, but the toolkit provides wider
       functionality than this.	The "cl::" constants can be combined with the
       "wc::" constants, that represent	standard widget	class.	The widget
       class is	implicitly used	when single "cl::" constant is used; its value
       is read from the	"::widgetClass"	property, unless one of	"wc::"
       constants is combined with the non-RGB "cl::" value. "wc::" constants
       are described in	"API"; their usage can make call of, for example,
       "backColor( cl::Back)" on a button and on an input line result in
       different colors, because the "cl::Back"	is translated in the first
       case into "cl::Back|wc::Button",	and in another -
       "cl::Back|wc::InputLine".

       Dynamic change of the color properties result in	the "ColorChanged"
       notification.

Fonts
       Prima::Widget does not change the handling of fonts - the font
       selection inside	and outside "begin_paint()"/"end_paint()" is not
       different at all. A matter of difference	is how does Prima::Widget
       select the default font.

       First, if the "::ownerFont" property is set to 1, then font of the
       owner is	copied to the widget, and is maintained	all the	time while the
       property	is true.  If it	is not,	the default font values	read from the
       system.

       The default font	metrics	for a widget returned by "get_default_font()"
       method, that often deals	with system-dependent and user-selected
       preferences ( see "Additional resources"	). Because a widget can	host
       an eventual Prima::Popup	object,	it contains "get_default_popup_font()"
       method, that returns the	default	font for the popup objects. The
       dynamic popup font settings governed, naturally,	by the "::popupFont"
       property. Prima::Window extends the functionality to
       "get_default_menu_font()" and the "::menuFont" property.

       Dynamic change of the font property results in the "FontChanged"
       notification.

Additional resources
       The resources, operated via Prima::Widget class but not that strictly
       bound to	the widget concept, are	gathered in this section. The section
       includes	overview of pointer, cursor, hint, menu	objects	and user-
       specified resources.

   Pointer
       The mouse pointer is the	shared resource, that can change its visual
       representation when it hovers over different kinds of widgets.  It is
       usually a good practice for a text field, for example, set the pointer
       icon to a jagged	vertical line, or indicate a moving window with	a
       cross-arrowed pointer.

       A widget	can select either one of the predefined	system pointers,
       mapped by the "cr::XXX" constant	set, or	supply its own pointer icon of
       an arbitrary size and color depth.

       NB: Not all systems allow the colored pointer icons. System value under
       sv::ColorPointer	index containing a boolean value, whether the colored
       icons are allowed or not.

       In general, the "::pointer" property is enough for these	actions.  It
       discerns	whether	it has an icon or a constant passed, and sets the
       appropriate properties. These properties	are also accessible
       separately, although their usage	is not encouraged, primarily because
       of the tangled relationship between them. These properties are:
       "::pointerType",	"::pointerIcon", and "::pointerHotSpot". See their
       details in the "API" sections.

       Another property, which is present only in Prima::Application name
       space is	called "::pointerVisible", and governs the visibility of the
       pointer - but for all widget instances at once.

   Cursor
       The cursor is a blinking	rectangular area, indicating the availability
       of the input focus in a widget. There can be only one active cursor per
       a GUI space, or none at all. Prima::Widget provides several cursor
       properties: "::cursorVisible", "::cursorPos", and "::cursorSize". There
       are also	two methods, "show_cursor()" and "hide_cursor()", which	are
       not the convenience shortcuts but the functions accounting the cursor
       hide count. If "hide_cursor()" was called three times, then
       "show_cursor()" must be called three times as well for the cursor to
       become visible.

   Hint
       "::hint"	is a text string, that usually describes the widget's purpose
       to the user in a	brief manner. If the mouse pointer is hovered over the
       widget longer than some timeout ( see Prima::Application::hintPause ),
       then a label appears with the hint text,	until the pointer is drawn
       away.  The hint behavior	is governed by Prima::Application, but a
       widget can do two additional things about hint: it can enable and
       disable it by calling "::showHint" property, and	it can inherit the
       owner's "::hint"	and "::showHint" properties using "::ownerHint"	and
       "::ownerShowHint" properties. If, for example, "::ownerHint" is set to
       1, then "::hint"	value is automatically copied from the widget's	owner,
       when it changes.	If, however, the widget's "::hint" or "::showHint" are
       explicitly set, the owner link breaks automatically by setting
       "::ownerHint" or	"::ownerShowHint" to 0.

       The widget can also operate the "::hintVisible" property, that shows or
       hides the hint label immediately, if the	mouse pointer is inside	the
       widget's	boundaries.

   Menu	objects
       The default functionality of Prima::Widget coexists with	two kinds of
       the Prima::AbstractMenu descendants - Prima::AccelTable and
       Prima::Popup ( Prima::Window is also equipped with Prima::Menu
       reference). The "::items" property of these objects are accessible
       through "::accelItems" and "::popupItems", whereas the objects
       themselves - through "::accelTable" and "::popup", correspondingly. As
       mentioned in "User input", these	objects	hook the user keyboard input
       and call	the programmer-defined callback	subroutine if the key stroke
       equals to one of	their table values. As for "::accelTable", its
       function	ends here. "::popup" provides access to	a context pop-up menu,
       which can be invoked by either right-clicking or	pressing a system-
       dependent key combination. As a little customization, the
       "::popupColorIndex" and "::popupFont" properties	are introduced.	 (
       "::popupColorIndex" is multiplexed to "::popupColor",
       "::popupHiliteColor", "::popupHiliteBackColor", etc etc properties
       exactly like the	"::colorIndex" property	).

       The font	and color of a menu object might not always be writable
       (Win32).

       The Prima::Window class provides	equivalent methods for the menu	bar,
       introducing "::menu", "::menuItems", "::menuColorIndex" ( with
       multiplexing ) and "::menuFont" properties.

   User-specified resources
       It is considered	a good idea to incorporate the user preferences	into
       the toolkit look-and-feel. Prima::Widget	relies to the system-specific
       code that tries to map these preferences	as close as possible to	the
       toolkit paradigm.

       Unix version employs XRDB ( X resource database ), which	is the natural
       way for the user	to tell	the preferences	with fine granularity. Win32
       reads the setting that the user has to set interactively, using system
       tools. Nevertheless, the	toolkit	can not	emulate	all user settings that
       are available on	the supported platforms; it rather takes a 'least
       common denominator', which is colors and	fonts. "fetch_resource()"
       method is capable of returning any of such settings, provided it's
       format is font, color or	a string.  The method is rarely	called
       directly.

       The appealing idea of making every widget property adjustable via the
       user-specified resources	is not implemented in full.  It	can be
       accomplished up to a certain degree using "fetch_resource()" existing
       functionality, but it is	believed that calling up the method for	the
       every property for the every widget created is prohibitively expensive.

API
   Properties
       accelItems [ ITEM_LIST ]
	   Manages items of a Prima::AccelTable	object associated with a
	   widget.  The	ITEM_LIST format is same as
	   "Prima::AbstractMenu::items"	and is described in Prima::Menu.

	   See also: "accelTable"

       accelTable OBJECT
	   Manages a Prima::AccelTable object associated with a	widget.	 The
	   sole	purpose	of the accelTable object is to provide convenience
	   mapping of key combinations to anonymous subroutines.  Instead of
	   writing an interface	specifically for Prima::Widget,	the existing
	   interface of	Prima::AbstractMenu was	taken.

	   The accelTable object can be	destroyed safely; its cancellation can
	   be done either via "accelTable(undef)" or "destroy()" call.

	   Default value: undef

	   See also: "accelItems"

       autoEnableChildren BOOLEAN
	   If TRUE, all	immediate children widgets maintain the	same "enabled"
	   state as the	widget.	This property is useful	for the	group-like
	   widgets ( ComboBox, SpinEdit	etc ), that employ their children for
	   visual representation.

	   Default value: 0

       backColor COLOR
	   In widget paint state, reflects background color in the graphic
	   context.  In	widget normal state, manages the basic background
	   color.  If changed, initiates "ColorChanged"	notification and
	   repaints the	widget.

	   See also: "color", "colorIndex", "ColorChanged"

       bottom INTEGER
	   Maintains the lower boundary	of a widget. If	changed, does not
	   affect the widget height; but does so, if called in "set()"
	   together with "::top".

	   See also: "left", "right", "top", "origin", "rect", "growMode",
	   "Move"

       briefKeys BOOLEAN
	   If 1, contracts the repetitive key press events into	one
	   notification, increasing REPEAT parameter of	"KeyDown" callbacks.
	   If 0, REPEAT	parameter is always 1.

	   Default value: 1

	   See also: "KeyDown"

       buffered	BOOLEAN
	   If 1, a widget "Paint" callback draws not on	the screen, but	on the
	   off-screen memory instead. The memory content is copied to the
	   screen then.	Used when complex drawing methods are used, or if
	   output smoothness is	desired.

	   This	behavior can not be always granted, however. If	there is not
	   enough memory, then widget draws in the usual manner.

	   Default value: 0

	   See also: "Paint"

       capture BOOLEAN,	CLIP_OBJECT = undef
	   Manipulates capturing of the	mouse events. If 1, the	mouse events
	   are not passed to the widget	the mouse pointer is over, but are
	   redirected to the caller widget. The	call for capture might not be
	   always granted due the race conditions between programs.

	   If CLIP_OBJECT widget is defined in set-mode	call, the pointer
	   movements are confined to CLIP_OBJECT inferior.

	   See also: "MouseDown", "MouseUp", "MouseMove", "MouseWheel",
	   "MouseClick".

       centered	BOOLEAN
	   A write-only	property. Once set, widget is centered by X and	Y axis
	   relative to its owner.

	   See also: "x_centered", "y_centered", "growMode", "origin", "Move".

       clipChildren BOOLEAN
	   Affects the drawing mode when children widgets are present and
	   obscuring the drawing area.	If set,	the children widgets are
	   automatically added to the clipping area, and drawing over them
	   will	not happen. If unset, the painting can be done over the
	   children widgets.

	   Default: 1

       clipOwner BOOLEAN
	   If 1, a widget is clipped by	its owner boundaries.  It is the
	   default and expected	behavior. If clipOwner is 0, a widget behaves
	   differently:	it does	not clipped by the owner, it is	not moved
	   together with the parent, the origin	offset is calculated not from
	   the owner's coordinates but from the	screen,	and mouse events in a
	   widget do not transgress to the top-level window decorations. In
	   short, it itself becomes a top-level	window,	that, contrary to the
	   one created from Prima::Window class, does not have any
	   interference	with system-dependent window stacking and positioning
	   ( and any other ) policy, and is not	ornamented by the window
	   manager decorations.

	   Default value: 1

	   See "Parent-child relationship"

	   See also: "Prima::Object" owner section, "parentHandle"

       color COLOR
	   In widget paint state, reflects foreground color in the graphic
	   context.  In	widget normal state, manages the basic foreground
	   color.  If changed, initiates "ColorChanged"	notification and
	   repaints the	widget.

	   See also: "backColor", "colorIndex",	"ColorChanged"

       colorIndex INDEX, COLOR
	   Manages the basic color properties indirectly, by accessing via
	   "ci::XXX" constant. Is a complete alias for "::color",
	   "::backColor", "::hiliteColor", "::hiliteBackColor",
	   "::disabledColor", "::disabledBackColor", "::light3DColor", and
	   "::dark3DColor" properties. The "ci::XXX" constants are:

	      ci::NormalText or	ci::Fore
	      ci::Normal or ci::Back
	      ci::HiliteText
	      ci::Hilite
	      ci::DisabledText
	      ci::Disabled
	      ci::Light3DColor
	      ci::Dark3DColor

	   The non-RGB "cl::" constants, specific to the Prima::Widget color
	   usage are identical to their	"ci::" counterparts:

	      cl::NormalText or	cl::Fore
	      cl::Normal or cl::Back
	      cl::HiliteText
	      cl::Hilite
	      cl::DisabledText
	      cl::Disabled
	      cl::Light3DColor
	      cl::Dark3DColor

	   See also: "color", "backColor", "ColorChanged"

       current BOOLEAN
	   If 1, a widget (or one of its children) is marked as	the one	to be
	   focused ( or	selected) when the owner widget	receives "select()"
	   call.  Within children widgets, only	one or none at all can be
	   marked as a current.

	   See also: "currentWidget", "selectable", "selected",
	   "selectedWidget", "focused"

       currentWidget OBJECT
	   Points to a children	widget,	that is	to be focused (	or selected)
	   when	the owner widget receives "select()" call.

	   See also: "current",	"selectable", "selected", "selectedWidget",
	   "focused"

       cursorPos X_OFFSET Y_OFFSET
	   Specifies the lower left corner of the cursor

	   See also: "cursorSize", "cursorVisible"

       cursorSize WIDTH	HEIGHT
	   Specifies width and height of the cursor

	   See also: "cursorPos", "cursorVisible"

       cursorVisible BOOLEAN
	   Specifies cursor visibility flag. Default value is 0.

	   See also: "cursorSize", "cursorPos"

       dark3DColor COLOR
	   The color used to draw dark shades.

	   See also: "light3DColor", "colorIndex", "ColorChanged"

       designScale X_SCALE Y_SCALE
	   The width and height	of a font, that	was used when a	widget (
	   usually  a dialog or	a grouping widget ) was	designed.

	   See also: "scaleChildren", "width", "height", "size", "font"

       disabledBackColor COLOR
	   The color used to substitute	"::backColor" when a widget is in its
	   disabled state.

	   See also: "disabledColor", "colorIndex", "ColorChanged"

       disabledColor COLOR
	   The color used to substitute	"::color" when a widget	is in its
	   disabled state.

	   See also: "disabledBackColor", "colorIndex",	"ColorChanged"

       enabled BOOLEAN
	   Specifies if	a widget can accept focus, keyboard and	mouse events.
	   Default value is 1, however,	being 'enabled'	does not automatically
	   allow the widget become focused. Only the reverse is	true - if
	   enabled is 0, focusing can never happen.

	   See also: "responsive", "visible", "Enable",	"Disable"

       font %FONT
	   Manages font	context. Same syntax as	in Prima::Drawable.  If
	   changed, initiates "FontChanged" notification and repaints the
	   widget.

	   See also: "designScale", "FontChanged", "ColorChanged"

       geometry	INTEGER
	   Selects one of the available	geometry managers. The corresponding
	   integer constants are:

	      gt::GrowMode, gt::Default	- the default grow-mode	algorithm
	      gt::Pack			- Tk packer
	      gt::Place			- Tk placer

	   See "growMode", Prima::Widget::pack,	Prima::Widget::place.

       growMode	MODE
	   Specifies widget behavior, when its owner is	resized	or moved.
	   MODE	can be 0 ( default ) or	a combination of the following
	   constants:

	   Basic constants
		gm::GrowLoX	 widget's left side is kept in constant
				 distance from owner's right side
		gm::GrowLoY	 widget's bottom side is kept in constant
				 distance from owner's top side
		gm::GrowHiX	 widget's right	side is	kept in	constant
				 distance from owner's right side
		gm::GrowHiY	 widget's top side is kept in constant
				 distance from owner's top side
		gm::XCenter	 widget	is kept	in center on its owner's
				 horizontal axis
		gm::YCenter	 widget	is kept	in center on its owner's
				 vertical axis
		gm::DontCare	 widgets origin	is maintained constant relative
				 to the	screen

	   Derived or aliased constants
		gm::GrowAll	 gm::GrowLoX|gm::GrowLoY|gm::GrowHiX|gm::GrowHiY
		gm::Center	 gm::XCenter|gm::YCenter
		gm::Client	 gm::GrowHiX|gm::GrowHiY
		gm::Right	 gm::GrowLoX|gm::GrowHiY
		gm::Left	 gm::GrowHiY
		gm::Floor	 gm::GrowHiX

	   See also: "Move", "origin"

       firstClick BOOLEAN
	   If 0, a widget bypasses first mouse click on	it, if the top-level
	   window it belongs to	was not	activated, so selecting	such a widget
	   it takes two	mouse clicks.

	   Default value is 1

	   See also: "MouseDown", "selectable",	"selected", "focused",
	   "selectingButtons"

       focused BOOLEAN
	   Specifies whether a widget possesses	the input focus	or not.
	   Disregards "::selectable" property on set-call.

	   See also: "selectable", "selected", "selectedWidget", "KeyDown"

       geomWidth, geomHeight, geomSize
	   Three properties that select	geometry request size. Writing and
	   reading to "::geomWidth" and	"::geomHeight" is equivalent to
	   "::geomSize". The properies are run-time only, and behave
	   differently under different circumstances:

	   o   As the properties are run-time only, they can not be set	in the
	       profile,	and their initial value	is fetched from	"::size"
	       property. Thus, setting the explicit size is aditionally	sets
	       the advised size	in case	the widget is to be used with the Tk
	       geometry	managers.

	   o   Setting the properties under the	"gt::GrowMode" geometry
	       manager also sets the corresponding "::width", "::height", or
	       "::size". When the properties are read, though, the real	size
	       properties are not read;	the values are kept separately.

	   o   Setting the properties under Tk geometry	managers cause widgets
	       size and	position changed according to the geometry manager
	       policy.

       height
	   Maintains the height	of a widget.

	   See also: "width", "growMode", "Move", "Size", "get_virtual_size",
	   "sizeMax", "sizeMin"

       helpContext STRING
	   A string that binds a widget, a logical part	it plays with the
	   application and an interactive help topic. STRING format is defined
	   as POD link ( see perlpod ) - "manpage/section", where 'manpage' is
	   the file with POD content and 'section' is the topic	inside the
	   manpage.

	   See also: "help"

       hiliteBackColor COLOR
	   The color used to draw alternate background areas with high
	   contrast.

	   See also: "hiliteColor", "colorIndex", "ColorChanged"

       hiliteColor COLOR
	   The color used to draw alternate foreground areas with high
	   contrast.

	   See also: "hiliteBackColor",	"colorIndex", "ColorChanged"

       hint TEXT
	   A text, shown under mouse pointer if	it is hovered over a widget
	   longer than "Prima::Application::hintPause" timeout.	The text shows
	   only	if the "::showHint" is 1.

	   See also: "hintVisible", "showHint",	"ownerHint", "ownerShowHint"

       hintVisible BOOLEAN
	   If called in	get-form, returns whether the hint label is shown or
	   not.	If in set-form,	immediately turns on or	off the	hint label,
	   disregarding	the timeouts. It does regard the mouse pointer
	   location, however, and does not turn	on the hint label if the
	   pointer is away.

	   See also: "hint", "showHint", "ownerHint", "ownerShowHint"

       layered BOOLEAN
	   If set, the widget will try to use alpha transparency available on
	   the system.	See "Layering" in Prima::Image for more	details.

	   Default: false

	   See also: "is_surface_layered"

	   Note: In Windows, mouse events will not be delivered	to the layered
	   widget if the pixel under the mouse pointer is fully	transparent.

	   In X11, you need to run a composition manager, f.ex.	compiz or
	   xcompmgr.

       left INTEGER
	   Maintains the left boundary of a widget. If changed,	does not
	   affect the widget width; but	does so, if called in "set()" together
	   with	"::right".

	   See also: "bottom", "right",	"top", "origin", "rect", "growMode",
	   "Move"

       light3DColor COLOR
	   The color used to draw light	shades.

	   See also: "dark3DColor", "colorIndex", "ColorChanged"

       ownerBackColor BOOLEAN
	   If 1, the background	color is synchronized with the owner's.
	   Automatically set to	0 if "::backColor" property is explicitly set.

	   See also: "ownerColor", "backColor",	"colorIndex"

       ownerColor BOOLEAN
	   If 1, the foreground	color is synchronized with the owner's.
	   Automatically set to	0 if "::color" property	is explicitly set.

	   See also: "ownerBackColor", "color",	"colorIndex"

       ownerFont BOOLEAN
	   If 1, the font is synchronized with the owner's.  Automatically set
	   to 0	if "::font" property is	explicitly set.

	   See also: "font", "FontChanged"

       ownerHint BOOLEAN
	   If 1, the hint is synchronized with the owner's.  Automatically set
	   to 0	if "::hint" property is	explicitly set.

	   See also: "hint", "showHint", "hintVisible",	"ownerShowHint"

       ownerShowHint BOOLEAN
	   If 1, the show hint flag is synchronized with the owner's.
	   Automatically set to	0 if "::showHint" property is explicitly set.

	   See also: "hint", "showHint", "hintVisible",	"ownerHint"

       ownerPalette BOOLEAN
	   If 1, the palette array is synchronized with	the owner's.
	   Automatically set to	0 if "::palette" property is explicitly	set.

	   See also: "palette"

       origin X	Y
	   Maintains the left and bottom boundaries of a widget	relative to
	   its owner ( or to the screen	if "::clipOwner" is set	to 0 ).

	   See also: "bottom", "right",	"top", "left", "rect", "growMode",
	   "Move"

       packInfo	%OPTIONS
	   See Prima::Widget::pack

       palette [ @PALETTE ]
	   Specifies array of colors, that are desired to be present into the
	   system palette, as close to the PALETTE as possible.	 This property
	   works only if the graphic device allows palette operations. See
	   "palette" in	Prima::Drawable.

	   See also: "ownerPalette"

       parentHandle SYSTEM_WINDOW
	   If SYSTEM_WINDOW is a valid system-dependent	window handle, then a
	   widget becomes the child of the window specified, given the
	   widget's "::clipOwner" is 0.	 The parent window can belong to
	   another application.

	   Default value is undef.

	   See also: "clipOwner"

       placeInfo %OPTIONS
	   See Prima::Widget::place

       pointer cr::XXX or ICON
	   Specifies the pointer icon; discerns	between	"cr::XXX" constants
	   and an icon.	If an icon contains a hash variable "__pointerHotSpot"
	   with	an array of two	integers, these	integers will be treated as
	   the pointer hot spot. In get-mode call, this	variable is
	   automatically assigned to an	icon, if the result is an icon object.

	   See also: "pointerHotSpot", "pointerIcon", "pointerType"

       pointerHotSpot X_OFFSET Y_OFFSET
	   Specifies the hot spot coordinates of a pointer icon, associated
	   with	a widget.

	   See also: "pointer",	"pointerIcon", "pointerType"

       pointerIcon ICON
	   Specifies the pointer icon, associated with a widget.

	   See also: "pointerHotSpot", "pointer", "pointerType"

       pointerPos X_OFFSET Y_OFFSET
	   Specifies the mouse pointer coordinates relative to widget's
	   coordinates.

	   See also: "get_mouse_state",	"screen_to_client", "client_to_screen"

       pointerType TYPE
	   Specifies the type of the pointer, associated with the widget.
	   TYPE	can accept one constant	of "cr::XXX" set:

	      cr::Default		  same pointer type as owner's
	      cr::Arrow			  arrow	pointer
	      cr::Text			  text entry cursor-like pointer
	      cr::Wait			  hourglass
	      cr::Size			  general size action pointer
	      cr::Move			  general move action pointer
	      cr::SizeWest, cr::SizeW	  right-move action pointer
	      cr::SizeEast, cr::SizeE	  left-move action pointer
	      cr::SizeWE		  general horizontal-move action pointer
	      cr::SizeNorth, cr::SizeN	  up-move action pointer
	      cr::SizeSouth, cr::SizeS	  down-move action pointer
	      cr::SizeNS		  general vertical-move	action pointer
	      cr::SizeNW		  up-right move	action pointer
	      cr::SizeSE		  down-left move action	pointer
	      cr::SizeNE		  up-left move action pointer
	      cr::SizeSW		  down-right move action pointer
	      cr::Invalid		  invalid action pointer
	      cr::User			  user-defined icon

	   All constants except	"cr::User" and "cr::Default" present a system-
	   defined pointers, their icons and hot spot offsets. "cr::User" is a
	   sign	that an	icon object was	specified explicitly via
	   "::pointerIcon" property.  "cr::Default" is a way to	tell that a
	   widget inherits its owner pointer type, no matter is	it a system-
	   defined pointer or a	custom icon.

	   See also: "pointerHotSpot", "pointerIcon", "pointer"

       popup OBJECT
	   Manages a Prima::Popup object associated with a widget.  The
	   purpose of the popup	object is to show a context menu when the user
	   right-clicks	or selects the corresponding keyboard combination.
	   Prima::Widget can host many children	objects, Prima::Popup as well.
	   But only the	one that is set	in "::popup" property will be
	   activated automatically.

	   The popup object can	be destroyed safely; its cancellation can be
	   done	either via "popup(undef)" or "destroy()" call.

	   See also: "Prima::Menu", "Popup", "Menu", "popupItems",
	   "popupColorIndex", "popupFont"

       popupColorIndex INDEX, COLOR
	   Maintains eight color properties of a pop-up	context	menu,
	   associated with a widget. INDEX must	be one of "ci::XXX" constants
	   ( see "::colorIndex"	property ).

	   See also: "popupItems", "popupFont",	"popup"

       popupColor COLOR
	   Basic foreground in a popup context menu color.

	   See also: "popupItems", "popupColorIndex", "popupFont", "popup"

       popupBackColor COLOR
	   Basic background in a popup context menu color.

	   See also: "popupItems", "popupColorIndex", "popupFont", "popup"

       popupDark3DColor	COLOR
	   Color for drawing dark shadings in a	popup context menu.

	   See also: "popupItems", "popupColorIndex", "popupFont", "popup"

       popupDisabledColor COLOR
	   Foreground color for	disabled items in a popup context menu.

	   See also: "popupItems", "popupColorIndex", "popupFont", "popup"

       popupDisabledBackColor COLOR
	   Background color for	disabled items in a popup context menu.

	   See also: "popupItems", "popupColorIndex", "popupFont", "popup"

       popupFont %FONT
	   Maintains the font of a pop-up context menu,	associated with	a
	   widget.

	   See also: "popupItems", "popupColorIndex", "popup"

       popupHiliteColor	COLOR
	   Foreground color for	selected items in a popup context menu.

	   See also: "popupItems", "popupColorIndex", "popupFont", "popup"

       popupHiliteBackColor COLOR
	   Background color for	selected items in a popup context menu.

	   See also: "popupItems", "popupColorIndex", "popupFont", "popup"

       popupItems [ ITEM_LIST ]
	   Manages items of a Prima::Popup object associated with a widget.
	   The ITEM_LIST format	is same	as "Prima::AbstractMenu::items"	and is
	   described in	Prima::Menu.

	   See also: "popup", "popupColorIndex", "popupFont"

       popupLight3DColor COLOR
	   Color for drawing light shadings in a popup context menu.

	   See also: "popupItems", "popupColorIndex", "popupFont", "popup"

       rect X_LEFT_OFFSET Y_BOTTOM_OFFSET X_RIGHT_OFFSET Y_TOP_OFFSET
	   Maintains the rectangular boundaries	of a widget relative to	its
	   owner ( or to the screen if "::clipOwner" is	set to 0 ).

	   See also: "bottom", "right",	"top", "left", "origin", "width",
	   "height", "size" "growMode",	"Move",	"Size",	"get_virtual_size",
	   "sizeMax", "sizeMin"

       right INTEGER
	   Maintains the right boundary	of a widget. If	changed, does not
	   affect the widget width; but	does so, if called in "set()" together
	   with	"::left".

	   See also: "left", "bottom", "top", "origin",	"rect",	"growMode",
	   "Move"

       scaleChildren BOOLEAN
	   If a	widget has "::scaleChildren" set to 1, then the	newly-created
	   children widgets inserted in	it will	be scaled corresponding	to the
	   owner's "::designScale", given that widget's	"::designScale"	is not
	   "undef" and the owner's is not [0,0].

	   Default is 1.

	   See also: "designScale"

       selectable BOOLEAN
	   If 1, a widget can be granted focus implicitly, or by means of the
	   user	actions. "select()" regards this property, and does not	focus
	   a widget that has "::selectable" set	to 0.

	   Default value is 0

	   See also: "current",	"currentWidget", "selected", "selectedWidget",
	   "focused"

       selected	BOOLEAN
	   If called in	get-mode, returns whether a widget or one of its
	   (grand-) children is	focused. If in set-mode, either	simply turns
	   the system with no-focus state ( if 0 ), or sends input focus to
	   itself or one of the	widgets	tracked	down by	"::currentWidget"
	   chain.

	   See also: "current",	"currentWidget", "selectable",
	   "selectedWidget", "focused"

       selectedWidget OBJECT
	   Points to a child widget, that has property "::selected" set	to 1.

	   See also: "current",	"currentWidget", "selectable", "selected",
	   "focused"

       selectingButtons	FLAGS
	   FLAGS is a combination of "mb::XXX" ( mouse button )	flags.	If a
	   widget receives a click with	a mouse	button,	that has the
	   corresponding bit set in "::selectingButtons", then "select()" is
	   called.

	   See also: "MouseDown", "firstClick",	"selectable", "selected",
	   "focused"

       shape REGION
	   Maintains the non-rectangular shape of a widget.  When setting,
	   REGION is either a Prima::Image object, with	0 bits treated as
	   transparent pixels, and 1 bits as opaque pixels, or a Prima::Region
	   object.  When getting, it is	either undef or	a Prima::Region
	   object.

	   Successive only if "sv::ShapeExtension" value is true.

       showHint	BOOLEAN
	   If 1, the toolkit is	allowed	to show	the hint label over a widget.
	   If 0, the display of	the hint is forbidden. The "::hint" property
	   must	contain	non-empty string as well, if the hint label must be
	   shown.

	   Default value is 1.

	   See also: "hint", "ownerShowHint", "hintVisible", "ownerHint"

       size WIDTH HEIGHT
	   Maintains the width and height of a widget.

	   See also: "width", "height" "growMode", "Move", "Size",
	   "get_virtual_size", "sizeMax", "sizeMin"

       sizeMax WIDTH HEIGHT
	   Specifies the maximal size for a widget that	it is allowed to
	   accept.

	   See also: "width", "height",	"size" "growMode", "Move", "Size",
	   "get_virtual_size", "sizeMin"

       sizeMin WIDTH HEIGHT
	   Specifies the minimal size for a widget that	it is allowed to
	   accept.

	   See also: "width", "height",	"size" "growMode", "Move", "Size",
	   "get_virtual_size", "sizeMax"

       syncPaint BOOLEAN
	   If 0, the "Paint" request notifications are stacked until the event
	   loop	is called. If 1, every time the	widget surface gets
	   invalidated,	the "Paint" notification is called.

	   Default value is 0.

	   See also: "invalidate_rect",	"repaint", "validate_rect", "Paint"

       tabOrder	INTEGER
	   Maintains the order in which	tab- and shift-tab- key	navigation
	   algorithms select the sibling widgets. INTEGER is unique among the
	   sibling widgets. In set mode, if INTEGER value is already taken,
	   the occupier	is assigned another unique value, but without
	   destruction of a queue - widgets with ::tabOrder greater than of
	   the widget, receive their new values	too. Special value -1 is
	   accepted as 'the end	of list' indicator; the	negative value is
	   never returned.

	   See also: "tabStop",	"next_tab", "selectable", "selected",
	   "focused"

       tabStop BOOLEAN
	   Specifies whether a widget is interested in tab- and	shift-tab- key
	   navigation or not.

	   Default value is 1.

	   See also: "tabOrder", "next_tab", "selectable", "selected",
	   "focused"

       text TEXT
	   A text string for generic purpose. Many Prima::Widget descendants
	   use this property heavily - buttons,	labels,	input lines etc, but
	   Prima::Widget itself	does not.

       top INTEGER
	   Maintains the upper boundary	of a widget. If	changed, does not
	   affect the widget height; but does so, if called in "set()"
	   together with "::bottom".

	   See also: "left", "right", "bottom",	"origin", "rect", "growMode",
	   "Move"

       transparent BOOLEAN
	   Specifies whether the background of a widget	before it starts
	   painting is of any importance. If 1,	a widget can gain certain
	   transparency	look if	it does	not clear the background during
	   "Paint" event.

	   Default value is 0

	   See also: "Paint", "buffered".

       visible BOOLEAN
	   Specifies whether a widget is visible or not.  See "Visibility".

	   See also: "Show", "Hide", "showing",	"exposed"

       widgetClass CLASS
	   Maintains the integer value,	designating the	color class that is
	   defined by the system and is	associated with	Prima::Widget eight
	   basic color properties. CLASS can be	one of "wc::XXX" constants:

	      wc::Undef
	      wc::Button
	      wc::CheckBox
	      wc::Combo
	      wc::Dialog
	      wc::Edit
	      wc::InputLine
	      wc::Label
	      wc::ListBox
	      wc::Menu
	      wc::Popup
	      wc::Radio
	      wc::ScrollBar
	      wc::Slider
	      wc::Widget or wc::Custom
	      wc::Window
	      wc::Application

	   These constants are not associated with the toolkit classes;	any
	   class can use any of	these constants	in "::widgetClass".

	   See also: "map_color", "colorIndex"

       widgets @WIDGETS
	   In get-mode,	returns	list of	immediate children widgets (identical
	   to "get_widgets"). In set-mode accepts set of widget	profiles, as
	   "insert" does, as a list or an array. This way it is	possible to
	   create widget hierarchy in a	single call.

       width WIDTH
	   Maintains the width of a widget.

	   See also: "height" "growMode", "Move", "Size", "get_virtual_size",
	   "sizeMax", "sizeMin"

       x_centered BOOLEAN
	   A write-only	property. Once set, widget is centered by the
	   horizontal axis relative to its owner.

	   See also: "centered", "y_centered", "growMode", "origin", "Move".

       y_centered BOOLEAN
	   A write-only	property. Once set, widget is centered by the vertical
	   axis	relative to its	owner.

	   See also: "x_centered", "centered", "growMode", "origin", "Move".

   Methods
       bring_to_front
	   Sends a widget on top of all	other siblings widgets

	   See also: "insert_behind", "send_to_back", "ZOrderChanged"
	   ,"first", "next", "prev", "last"

       can_close
	   Sends "Close" message, and returns its boolean exit state.

	   See also: "Close", "close"

       client_to_screen	@OFFSETS
	   Maps	array of X and Y integer offsets from widget to	screen
	   coordinates.	 Returns the mapped OFFSETS.

	   See also: "screen_to_client", "clipOwner"

       close
	   Calls "can_close()",	and if successful, destroys a widget.  Returns
	   the "can_close()" result.

	   See also: "can_close", "Close"

       defocus
	   Alias for focused(0)	call

	   See also: "focus", "focused", "Enter", "Leave"

       deselect
	   Alias for selected(0) call

	   See also: "select", "selected", "Enter", "Leave"

       exposed
	   Returns a boolean value, indicating whether a widget	is at least
	   partly visible on the screen.  Never	returns	1 if a widget has
	   "::visible" set to 0.

	   See also: "visible",	"showing", "Show", "Hide"

       fetch_resource CLASS_NAME, NAME,	CLASS_RESOURCE,	RESOURCE, OWNER,
       RESOURCE_TYPE = fr::String
	   Returns a system-defined scalar of resource,	defined	by the widget
	   hierarchy, its class, name and owner. RESOURCE_TYPE can be one of
	   type	qualificators:

	      fr::Color	 - color resource
	      fr::Font	 - font	resource
	      fs::String - text	string resource

	   Such	a number of the	parameters is used because the method can be
	   called before a widget is created.  CLASS_NAME is widget class
	   string, NAME	is widget name.	 CLASS_RESOURCE	is class of resource,
	   and RESOURCE	is the resource	name.

	   For example,	resources 'color' and 'disabledColor' belong to	the
	   resource class 'Foreground'.

       first
	   Returns the first ( from bottom ) sibling widget in Z-order.

	   See also: "last", "next", "prev"

       focus
	   Alias for focused(1)	call

	   See also: "defocus",	"focused", "Enter", "Leave"

       hide
	   Sets	widget "::visible" to 0.

	   See also: "hide", "visible",	"Show",	"Hide",	"showing", "exposed"

       hide_cursor
	   Hides the cursor. As	many times "hide_cursor()" was called, as many
	   time	its counterpart	"show_cursor()"	must be	called to reach	the
	   cursor's initial state.

	   See also: "show_cursor", "cursorVisible"

       help
	   Starts an interactive help viewer opened on "::helpContext" string
	   value.

	   The string value is combined	from the widget's owner
	   "::helpContext" strings if the latter is empty or begins with a
	   slash.  A special meaning is	assigned to an empty string " "	- the
	   help() call fails when such value is	found to be the	section
	   component.  This feature can	be useful when a window	or a dialog
	   presents a standalone functionality in a separate module, and the
	   documentation is related more to the	module than to an embedding
	   program. In such case, the grouping widget holds "::helpContext" as
	   a pod manpage name with a trailing slash, and its children widgets
	   are assigned	"::helpContext"	to the topics without the manpage but
	   the leading slash instead.  If the grouping widget has an empty
	   string " " as "::helpContext" then the help is forced to be
	   unavailable for all the children widgets.

	   See also: "helpContext"

       insert CLASS, %PROFILE [[ CLASS,	%PROFILE], ... ]
	   Creates one or more widgets with "owner" property set to the	caller
	   widget, and returns the list	of references to the newly created
	   widgets.

	   Has two calling formats:

	   Single widget
		 $parent-> insert( 'Child::Class',
		    name => 'child',
		    ....
		 );

	   Multiple widgets
		 $parent-> insert(
		   [
		      'Child::Class1',
			 name => 'child1',
			 ....
		   ],
		   [
		      'Child::Class2',
			 name => 'child2',
			 ....
		   ],
		 );

       insert_behind OBJECT
	   Sends a widget behind the OBJECT on Z-axis, given that the OBJECT
	   is a	sibling	to the widget.

	   See also: "bring_to_front", "send_to_back", "ZOrderChanged"
	   ,"first", "next", "prev", "last"

       invalidate_rect X_LEFT_OFFSET Y_BOTTOM_OFFSET X_RIGHT_OFFSET
       Y_TOP_OFFSET
	   Marks the rectangular area of a widget as 'invalid',	so re-painting
	   of the area happens.	See "Graphic content".

	   See also: "validate_rect", "get_invalid_rect", "repaint", "Paint",
	   "syncPaint",	"update_view"

       is_surface_layered
	   Returns true	if both	the widget and it's top-most parent are
	   layered.  If	the widget itself is top-most, i.e. a window, a	non-
	   clipOwner widget, or	a child	to application,	then is	the same as
	   "layered".

	   See also: layered

       key_down	CODE, KEY = kb::NoKey, MOD = 0,	REPEAT = 1, POST = 0
	   The method sends or posts ( POST flag ) simulated "KeyDown" event
	   to the system. CODE,	KEY, MOD and REPEAT are	the parameters to be
	   passed to the notification callbacks.

	   See also: "key_up", "key_event", "KeyDown"

       key_event COMMAND, CODE,	KEY = kb::NoKey, MOD = 0, REPEAT = 1, POST = 0
	   The method sends or posts ( POST flag ) simulated keyboard event to
	   the system. CODE, KEY, MOD and REPEAT are the parameters to be
	   passed to an	eventual "KeyDown" or "KeyUp" notifications.  COMMAND
	   is allowed to be either "cm::KeyDown" or "cm::KeyUp".

	   See also: "key_down", "key_up", "KeyDown", "KeyUp"

       key_up CODE, KEY	= kb::NoKey, MOD = 0, POST = 0
	   The method sends or posts ( POST flag ) simulated "KeyUp" event to
	   the system. CODE, KEY and MOD are the parameters to be passed to
	   the notification callbacks.

	   See also: "key_down", "key_event", "KeyUp"

       last
	   Returns the last ( the topmost ) sibling widget in Z-order.

	   See also: "first", "next", "prev"

       lock
	   Turns off the ability of a widget to	re-paint itself.  As many
	   times "lock()" was called, as may times its counterpart, "unlock()"
	   must	be called to enable re-painting	again.	Returns	a boolean
	   success flag.

	   See also: "unlock", "repaint", "Paint", "get_locked"

       map_color COLOR
	   Transforms "cl::XXX"	and "ci::XXX" combinations into	RGB color
	   representation and returns the result. If COLOR is already in RGB
	   format, no changes are made.

	   See also: "colorIndex"

       mouse_click BUTTON = mb::Left, MOD = 0, X = 0, Y	= 0, DBL_CLICK = 0,
       POST = 0
	   The method sends or posts ( POST flag ) simulated "MouseClick"
	   event to the	system.	BUTTON,	MOD, X,	Y, and DBL_CLICK are the
	   parameters to be passed to the notification callbacks.

	   See also: "MouseDown", "MouseUp", "MouseWheel", "MouseMove",
	   "MouseEnter", "MouseLeave"

       mouse_down BUTTON = mb::Left, MOD = 0, X	= 0, Y = 0, POST = 0
	   The method sends or posts ( POST flag ) simulated "MouseDown" event
	   to the system. BUTTON, MOD, X, and Y	are the	parameters to be
	   passed to the notification callbacks.

	   See also: "MouseUp",	"MouseWheel", "MouseClick", "MouseMove",
	   "MouseEnter", "MouseLeave"

       mouse_enter MOD = 0, X =	0, Y = 0, POST = 0
	   The method sends or posts ( POST flag ) simulated "MouseEnter"
	   event to the	system.	MOD, X,	and Y are the parameters to be passed
	   to the notification callbacks.

	   See also: "MouseDown", "MouseUp", "MouseWheel", "MouseClick",
	   "MouseMove",	"MouseLeave"

       mouse_event COMMAND = cm::MouseDown, BUTTON = mb::Left, MOD = 0,	X = 0,
       Y = 0, DBL_CLICK	= 0, POST = 0
	   The method sends or posts ( POST flag ) simulated mouse event to
	   the system. BUTTON, MOD, X, Y and DBL_CLICK are the parameters to
	   be passed to	an eventual mouse notifications.  COMMAND is allowed
	   to be one of	"cm::MouseDown", "cm::MouseUp",	"cm::MouseWheel",
	   "cm::MouseClick", "cm::MouseMove", "cm::MouseEnter",
	   "cm::MouseLeave" constants.

	   See also: "mouse_down", "mouse_up", "mouse_wheel", "mouse_click",
	   "mouse_move", "mouse_enter",	"mouse_leave", "MouseDown", "MouseUp",
	   "MouseWheel", "MouseClick", "MouseMove", "MouseEnter", "MouseLeave"

       mouse_leave
	   The method sends or posts ( POST flag ) simulated "MouseLeave"
	   event to the	system.

	   See also: "MouseDown", "MouseUp", "MouseWheel", "MouseClick",
	   "MouseMove",	"MouseEnter", "MouseLeave"

       mouse_move MOD =	0, X = 0, Y = 0, POST =	0
	   The method sends or posts ( POST flag ) simulated "MouseMove" event
	   to the system. MOD, X, and Y	are the	parameters to be passed	to the
	   notification	callbacks.

	   See also: "MouseDown", "MouseUp", "MouseWheel", "MouseClick",
	   "MouseEnter", "MouseLeave"

       mouse_up	BUTTON = mb::Left, MOD = 0, X =	0, Y = 0, POST = 0
	   The method sends or posts ( POST flag ) simulated "MouseUp" event
	   to the system. BUTTON, MOD, X, and Y	are the	parameters to be
	   passed to the notification callbacks.

	   See also: "MouseDown", "MouseWheel",	"MouseClick", "MouseMove",
	   "MouseEnter", "MouseLeave"

       mouse_wheel MOD = 0, X =	0, Y = 0, INCR = 0, POST = 0
	   The method sends or posts ( POST flag ) simulated "MouseUp" event
	   to the system. MOD, X, Y and	INCR are the parameters	to be passed
	   to the notification callbacks.

	   See also: "MouseDown", "MouseUp", "MouseClick", "MouseMove",
	   "MouseEnter", "MouseLeave"

       next
	   Returns the neighbor	sibling	widget,	next ( above ) in Z-order.  If
	   none	found, undef is	returned.

	   See also: "first", "last", "prev"

       next_tab	FORWARD	= 1
	   Returns the next widget in the sorted by "::tabOrder" list of
	   sibling widgets. FORWARD is a boolean lookup	direction flag.	 If
	   none	found, the first ( or the last,	depending on FORWARD flag )
	   widget is returned. Only widgets with "::tabStop" set to 1
	   participate.

	   Also	used by	the internal keyboard navigation code.

	   See also: "next_positional",	"tabOrder", "tabStop", "selectable"

       next_positional DELTA_X DELTA_Y
	   Returns a sibling, (grand-)child of a sibling or (grand-)child
	   widget, that	matched	best the direction specified by	DELTA_X	and
	   DELTA_Y.  At	one time, only one of these parameters can be zero;
	   another parameter must be either 1 or -1.

	   Also	used by	the internal keyboard navigation code.

	   See also: "next_tab", "origin"

       pack, packForget, packSlaves
	   See Prima::Widget::pack

       place, placeForget, placeSlaves
	   See Prima::Widget::place

       prev
	   Returns the neighbor	sibling	widget,	previous ( below ) in Z-order.
	   If none found, undef	is returned.

	   See also: "first", "last", "next"

       repaint
	   Marks the whole widget area as 'invalid', so	re-painting of the
	   area	happens. See "Graphic content".

	   See also: "validate_rect", "get_invalid_rect", "invalidate_rect",
	   "Paint", "update_view", "syncPaint"

       rect_bevel $CANVAS, @RECT, %OPTIONS
	   Draws a rectangular area, similar to	produced by "rect3d" over
	   @RECT that is 4-integer coordinates of the area, but	implicitly
	   using widget's "light3DColor" and "dark3DColor" properties' values.
	   The following options are recognized:

	   fill	COLOR
	       If set, the area	is filled with COLOR, ortherwise is left
	       intact.

	   width INTEGER
	       Width of	the border in pixels

	   concave BOOLEAN
	       If 1, draw a concave area, bulged otherwise

       responsive
	   Returns a boolean flag, indicating whether a	widget and its owners
	   have	all "::enabled"	1 or not. Useful for fast check	if a widget
	   should respond to the user actions.

	   See also: "enabled"

       screen_to_client	@OFFSETS
	   Maps	array of X and Y integer offsets from screen to	widget
	   coordinates.	 Returns the mapped OFFSETS.

	   See also: "client_to_screen"

       scroll DELTA_X DELTA_Y %OPTIONS
	   Scrolls the graphic context area by DELTA_X and DELTA_Y pixels.
	   OPTIONS is hash, that contains optional parameters to the scrolling
	   procedure:

	   clipRect [X1, Y1, X2, Y2]
	       The clipping area is confined by	X1, Y1,	X2, Y2 rectangular
	       area.  If not specified,	the clipping area covers the whole
	       widget.	Only the bits, covered by clipRect are affected.  Bits
	       scrolled	from the outside of the	rectangle to the inside	are
	       painted;	bits scrolled from the inside of the rectangle to the
	       outside are not painted.

	   confineRect [X1, Y1,	X2, Y2]
	       The scrolling area is confined by X1, Y1, X2, Y2	rectangular
	       area.  If not specified,	the scrolling area covers the whole
	       widget.

	   withChildren	BOOLEAN
	       If 1, the scrolling performs with the eventual children widgets
	       change their positions to DELTA_X and DELTA_Y as	well.

	   Cannot be used inside paint state.

	   See also: "Paint", "get_invalid_rect"

       select
	   Alias for selected(1) call

	   See also: "deselect", "selected", "Enter", "Leave"

       send_to_back
	   Sends a widget at bottom of all other siblings widgets

	   See also: "insert_behind", "bring_to_front",	"ZOrderChanged"
	   ,"first", "next", "prev", "last"

       show
	   Sets	widget "::visible" to 1.

	   See also: "hide", "visible",	"Show",	"Hide",	"showing", "exposed"

       show_cursor
	   Shows the cursor. As	many times "hide_cursor()" was called, as many
	   time	its counterpart	"show_cursor()"	must be	called to reach	the
	   cursor's initial state.

	   See also: "hide_cursor", "cursorVisible"

       showing
	   Returns a boolean value, indicating whether the widget and its
	   owners have all "::visible" 1 or not.

       unlock
	   Turns on the	ability	of a widget to re-paint	itself.	 As many times
	   "lock()" was	called,	as may times its counterpart, "unlock()" must
	   be called to	enable re-painting again.  When	last "unlock()"	is
	   called, an implicit "repaint()" call	is made.  Returns a boolean
	   success flag.

	   See also: "lock", "repaint",	"Paint", "get_locked"

       update_view
	   If any parts	of a widget were marked	as 'invalid' by	either
	   "invalidate_rect()" or "repaint()" calls or the exposure caused by
	   window movements ( or any other), then "Paint" notification is
	   immediately called.	If no parts are	invalid, no action is
	   performed.  If a widget has "::syncPaint" set to 1, "update_view()"
	   is always a no-operation call.

	   See also: "invalidate_rect",	"get_invalid_rect", "repaint",
	   "Paint", "syncPaint", "update_view"

       validate_rect X_LEFT_OFFSET Y_BOTTOM_OFFSET X_RIGHT_OFFSET Y_TOP_OFFSET
	   Reverses the	effect of "invalidate_rect()", restoring the original,
	   'valid' state of widget area	covered	by the rectangular area
	   passed. If a	widget with previously invalid areas was wholly
	   validated by	this method, no	"Paint"	notifications occur.

	   See also: "invalidate_rect",	"get_invalid_rect", "repaint",
	   "Paint", "syncPaint", "update_view"

   Get-methods
       get_default_font
	   Returns the default font for	a Prima::Widget	class.

	   See also: "font"

       get_default_popup_font
	   Returns the default font for	a Prima::Popup class.

	   See also: "font"

       get_invalid_rect
	   Returns the result of successive calls "invalidate_rect()",
	   "validate_rect()" and "repaint()", as a rectangular area ( four
	   integers ) that cover all invalid regions in	a widget.  If none
	   found, (0,0,0,0) is returned.

	   See also: "validate_rect", "invalidate_rect", "repaint", "Paint",
	   "syncPaint",	"update_view"

       get_handle
	   Returns a system handle for a widget

	   See also: "get_parent_handle", "Window::get_client_handle"

       get_locked
	   Returns 1 if	a widget is in "lock()"	- initiated repaint-blocked
	   state.

	   See also: "lock", "unlock"

       get_mouse_state
	   Returns a combination of "mb::XXX" constants, reflecting the
	   currently pressed mouse buttons.

	   See also: "pointerPos", "get_shift_state"

       get_parent
	   Returns the owner widget that clips the widget boundaries, or
	   application object if a widget is top-level.

	   See also: "clipOwner"

       get_parent_handle
	   Returns a system handle for a parent	of a widget, a window that
	   belongs to another program. Returns 0 if the	widget's owner and
	   parent are in the same application and process space.

	   See also: "get_handle", "clipOwner"

       get_pointer_size
	   Returns two integers, width and height of a icon, that the system
	   accepts as valid for	a pointer.  If the icon	is supplied that is
	   more	or less	than these values, it is truncated or padded with
	   transparency	bits, but is not stretched.  Can be called with	class
	   syntax.

       get_shift_state
	   Returns a combination of "km::XXX" constants, reflecting the
	   currently pressed keyboard modificator buttons.

	   See also: "get_shift_state"

       get_virtual_size
	   Returns virtual width and height of a widget.  See "Geometry",
	   Implicit size regulations.

	   See also: "width", "height",	"size" "growMode", "Move", "Size",
	   "sizeMax", "sizeMin"

       get_widgets
	   Returns list	of children widgets.

   Events
       Change
	   Generic notification, used for Prima::Widget	descendants;
	   Prima::Widget itself	neither	calls not uses the event.  Designed to
	   be called when an arbitrary major state of a	widget is changed.

       Click
	   Generic notification, used for Prima::Widget	descendants;
	   Prima::Widget itself	neither	calls not uses the event.  Designed to
	   be called when an arbitrary major action for	a widget is called.

       Close
	   Triggered by	"can_close()" and "close()" functions.	If the event
	   flag	is cleared during execution, these functions fail.

	   See also: "close", "can_close"

       ColorChanged INDEX
	   Called when one of widget's color properties	is changed, either by
	   direct property change or by	the system. INDEX is one of "ci::XXX"
	   constants.

	   See also: "colorIndex"

       Disable
	   Triggered by	a successive enabled(0)	call

	   See also: "Enable", "enabled", "responsive"

       DragDrop	X Y
	   Design in progress. Supposed	to be triggered	when a drag-and-drop
	   session started by the widget.  X and Y are mouse pointer
	   coordinates on the session start.

	   See also: "DragOver", "EndDrag"

       DragOver	X Y STATE
	   Design in progress. Supposed	to be called when a mouse pointer is
	   passed over a widget	during a drag-and-drop session.	 X and Y are
	   mouse pointer coordinates, identical	to "MouseMove" X Y parameters.
	   STATE value is undefined.

	   See also: "DragDrop", "EndDrag"

       Enable
	   Triggered by	a successive enabled(1)	call

	   See also: "Disable",	"enabled", "responsive"

       EndDrag X Y
	   Design in progress. Supposed	to be called when a drag-and-drop
	   session is finished successfully over a widget. X and Y are mouse
	   pointer coordinates on the session end.

	   See also: "DragDrop", "DragOver"

       Enter
	   Called when a widget	receives the input focus.

	   See also: "Leave", "focused", "selected"

       FontChanged
	   Called when a widget	font is	changed	either by direct property
	   change or by	the system.

	   See also: "font", "ColorChanged"

       Hide
	   Triggered by	a successive visible(0)	call

	   See also: "Show", "visible",	"showing", "exposed"

       Hint SHOW_FLAG
	   Called when the hint	label is about to show or hide,	depending on
	   SHOW_FLAG. The hint show or hide action fails, if the event flag is
	   cleared during execution.

	   See also: "showHint", "ownerShowHint", "hintVisible", "ownerHint"

       KeyDown CODE, KEY, MOD, REPEAT
	   Sent	to the focused widget when the user presses a key.  CODE
	   contains an eventual	character code,	KEY is one of "kb::XXX"
	   constants, MOD is a combination of the modificator keys pressed
	   when	the event occurred ( "km::XXX" ). REPEAT is how	many times the
	   key was pressed; usually it is 1.  (	see "::briefKeys" ).

	   The valid "km::" constants are:

	      km::Shift
	      km::Ctrl
	      km::Alt
	      km::KeyPad
	      km::DeadKey
	      km::Unicode

	   The valid "kb::" constants are grouped in several sets.  Some codes
	   are aliased,	like, "kb::PgDn" and "kb::PageDown".

	   Modificator keys
		  kb::ShiftL   kb::ShiftR   kb::CtrlL	   kb::CtrlR
		  kb::AltL     kb::AltR	    kb::MetaL	   kb::MetaR
		  kb::SuperL   kb::SuperR   kb::HyperL	   kb::HyperR
		  kb::CapsLock kb::NumLock  kb::ScrollLock kb::ShiftLock

	   Keys	with character code defined
		  kb::Backspace	 kb::Tab    kb::Linefeed   kb::Enter
		  kb::Return	 kb::Escape kb::Esc	   kb::Space

	   Function keys
		  kb::F1 .. kb::F30
		  kb::L1 .. kb::L10
		  kb::R1 .. kb::R10

	   Other
		  kb::Clear    kb::Pause   kb::SysRq  kb::SysReq
		  kb::Delete   kb::Home	   kb::Left   kb::Up
		  kb::Right    kb::Down	   kb::PgUp   kb::Prior
		  kb::PageUp   kb::PgDn	   kb::Next   kb::PageDown
		  kb::End      kb::Begin   kb::Select kb::Print
		  kb::PrintScr kb::Execute kb::Insert kb::Undo
		  kb::Redo     kb::Menu	   kb::Find   kb::Cancel
		  kb::Help     kb::Break   kb::BackTab

	   See also: "KeyUp", "briefKeys", "key_down", "help", "popup",
	   "tabOrder", "tabStop", "accelTable"

       KeyUp CODE, KEY,	MOD
	   Sent	to the focused widget when the user releases a key.  CODE
	   contains an eventual	character code,	KEY is one of "kb::XXX"
	   constants, MOD is a combination of the modificator keys pressed
	   when	the event occurred ( "km::XXX" ).

	   See also: "KeyDown",	"key_up"

       Leave
	   Called when the input focus is removed from a widget

	   See also: "Enter", "focused", "selected"

       Menu MENU VAR_NAME
	   Called before the user-navigated menu ( pop-up or pull-down ) is
	   about to show another level of submenu on the screen. MENU is
	   Prima::AbstractMenu descendant, that	children to a widget, and
	   VAR_NAME is the name	of the menu item that is about to be shown.

	   Used	for making changes in the menu structures dynamically.

	   See also: "popupItems"

       MouseClick BUTTON, MOD, X, Y, DOUBLE_CLICK
	   Called when a mouse click ( button is pressed, and then released
	   within system-defined interval of time ) is happened	in the widget
	   area. BUTTON	is one of "mb::XXX" constants, MOD is a	combination of
	   "km::XXX" constants,	reflecting pressed modificator keys during the
	   event, X and	Y are the mouse	pointer	coordinates. DOUBLE_CLICK is a
	   boolean flag, set to	1 if it	was a double click, 0 if a single.

	   "mb::XXX" constants are:

	      mb::b1 or	mb::Left
	      mb::b2 or	mb::Middle
	      mb::b3 or	mb::Right
	      mb::b4
	      mb::b5
	      mb::b6
	      mb::b7
	      mb::b8

	   See also: "MouseDown", "MouseUp", "MouseWheel", "MouseMove",
	   "MouseEnter", "MouseLeave"

       MouseDown BUTTON, MOD, X, Y
	   Occurs when the user	presses	mouse button on	a widget.  BUTTON is
	   one of "mb::XXX" constants, MOD is a	combination of "km::XXX"
	   constants, reflecting the pressed modificator keys during the
	   event, X and	Y are the mouse	pointer	coordinates.

	   See also: "MouseUp",	"MouseClick", "MouseWheel", "MouseMove",
	   "MouseEnter", "MouseLeave"

       MouseEnter MOD, X, Y
	   Occurs when the mouse pointer is entered the	area occupied by a
	   widget ( without mouse button pressed ).  MOD is a combination of
	   "km::XXX" constants,	reflecting the pressed modificator keys	during
	   the event, X	and Y are the mouse pointer coordinates.

	   See also: "MouseDown", "MouseUp", "MouseClick", "MouseWheel",
	   "MouseMove",	"MouseLeave"

       MouseLeave
	   Occurs when the mouse pointer is driven off the area	occupied by a
	   widget ( without mouse button pressed ).

	   See also: "MouseDown", "MouseUp", "MouseClick", "MouseWheel",
	   "MouseMove",	"MouseEnter"

       MouseMove MOD, X, Y
	   Occurs when the mouse pointer is transported	over a widget.	MOD is
	   a combination of  "km::XXX" constants, reflecting the pressed
	   modificator keys during the event, X	and Y are the mouse pointer
	   coordinates.

	   See also: "MouseDown", "MouseUp", "MouseClick", "MouseWheel",
	   "MouseEnter", "MouseLeave"

       MouseUp BUTTON, MOD, X, Y
	   Occurs when the user	depresses mouse	button on a widget.  BUTTON is
	   one of "mb::XXX" constants, MOD is a	combination of "km::XXX"
	   constants, reflecting the pressed modificator keys during the
	   event, X and	Y are the mouse	pointer	coordinates.

	   See also: "MouseDown", "MouseClick",	"MouseWheel", "MouseMove",
	   "MouseEnter", "MouseLeave"

       MouseWheel MOD, X, Y, INCR
	   Occurs when the user	rotates	mouse wheel on a widget.  MOD is a
	   combination of "km::XXX" constants, reflecting the pressed
	   modificator keys during the event, INCR is the wheel	movement,
	   scaled by 120.  +120	is a step upwards, or -120 downwards.  For
	   wheels which	are discrete button clicks INCR	is +/-120 but other
	   devices may give other amounts.  A widget should scroll by INCR/120
	   many	units, or partial unit,	for whatever its unit of movement
	   might be, such as lines of text, slider ticks, etc.

	   A widget might like to vary its unit	move according to the MOD
	   keys.  For example "Prima::SpinEdit"	has a "step" and "pageStep"
	   and moves by	"pageStep" when	"km::Ctrl" is held down	(see
	   Prima::Sliders).

	   See also: "MouseDown", "MouseUp", "MouseClick", "MouseMove",
	   "MouseEnter", "MouseLeave"

       Move OLD_X, OLD_Y, NEW_X, NEW_Y
	   Triggered when widget changes its position relative to its parent,
	   either by Prima::Widget methods or by the user.  OLD_X and OLD_Y
	   are the old coordinates of a	widget,	NEW_X and NEW_Y	are the	new
	   ones.

	   See also: "Size", "origin", "growMode", "centered", "clipOwner"

       Paint CANVAS
	   Caused when the system calls	for the	refresh	of a graphic context,
	   associated with a widget. CANVAS is the widget itself, however its
	   usage instead of widget is recommended ( see	"Graphic content" ).

	   See also: "repaint",	"syncPaint", "get_invalid_rect", "scroll",
	   "colorIndex", "font"

       Popup BY_MOUSE, X, Y
	   Called by the system	when the user presses a	key or mouse
	   combination defined for a context pop-up menu execution.  By
	   default executes the	associated Prima::Popup	object,	if it is
	   present. If the event flag is cleared during	the execution of
	   callbacks, the pop-up menu is not shown.

	   See also: "popup"

       Setup
	   This	message	is posted right	after "Create" notification, and comes
	   first from the event	loop. Prima::Widget does not use it.

       Show
	   Triggered by	a successive visible(1)	call

	   See also: "Show", "visible",	"showing", "exposed"

       Size OLD_WIDTH, OLD_HEIGHT, NEW_WIDTH, NEW_HEIGHT
	   Triggered when widget changes its size, either by Prima::Widget
	   methods or by the user.  OLD_WIDTH and OLD_HEIGHT are the old
	   extensions of a widget, NEW_WIDTH and NEW_HEIGHT are	the new	ones.

	   See also: "Move", "origin", "size", "growMode", "sizeMax",
	   "sizeMin", "rect", "clipOwner"

       SysHandle
	   Same	as in "Component", but introduces the following	"Widget"
	   properties can trigger it:

	   clipOwner, syncPaint, layered, transparent

	   This	event will be only needed when the system handle (that can be
	   acquired by "get_handle" ) is needed.

       TranslateAccel CODE, KEY, MOD
	   A distributed "KeyDown" event. Traverses all	the object tree	that
	   the widget which received original "KeyDown"	event belongs to. Once
	   the event flag is cleared, the iteration stops.

	   Used	for tracking keyboard events by	out-of-focus widgets.

	   See also: "KeyDown"

       ZOrderChanged
	   Triggered when a widget changes its stacking	order, or Z-order
	   among its siblings, either by Prima::Widget methods or by the user.

	   See also: "bring_to_front", "insert_behind",	"send_to_back"

AUTHOR
       Dmitry Karasik, <dmitry@karasik.eu.org>.

SEE ALSO
       Prima, Prima::Object, Prima::Drawable.

perl v5.24.1			  2017-05-15		 pod::Prima::Widget(3)

NAME | SYNOPSIS | DESCRIPTION | USAGE | Creation and destruction | Graphic content | Geometry | Z-order | Parent-child relationship | Visibility | Focus | User input | Color schemes | Fonts | Additional resources | API | AUTHOR | SEE ALSO

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