man/mann/focus.n - toolchains/skids - Git at Google

 '\"
 '\" Copyright (c) 1990-1994 The Regents of the University of California.
 '\" Copyright (c) 1994-1996 Sun Microsystems, Inc.
 '\"
 '\" See the file "license.terms" for information on usage and redistribution
 '\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
 '\"
 '\" RCS: @(#) $Id: focus.n,v 1.2 1998/09/14 18:22:56 stanton Exp $
 '\"
 '\" The definitions below are for supplemental macros used in Tcl/Tk
 '\" manual entries.
 '\"
 '\" .AP type name in/out ?indent?
 '\"	Start paragraph describing an argument to a library procedure.
 '\"	type is type of argument (int, etc.), in/out is either "in", "out",
 '\"	or "in/out" to describe whether procedure reads or modifies arg,
 '\"	and indent is equivalent to second arg of .IP (shouldn't ever be
 '\"	needed;  use .AS below instead)
 '\"
 '\" .AS ?type? ?name?
 '\"	Give maximum sizes of arguments for setting tab stops.  Type and
 '\"	name are examples of largest possible arguments that will be passed
 '\"	to .AP later.  If args are omitted, default tab stops are used.
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 '\"	of man pages.  The first argument is ignored and used for recording
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 '\"	options follow on successive lines, in four columns separated
 '\"	by tabs.
 '\"
 '\" .SE
 '\"	End of list of standard options for a Tk widget.
 '\"
 '\" .OP cmdName dbName dbClass
 '\"	Start of description of a specific option.  cmdName gives the
 '\"	option's name as specified in the class command, dbName gives
 '\"	the option's name in the option database, and dbClass gives
 '\"	the option's class in the option database.
 '\"
 '\" .UL arg1 arg2
 '\"	Print arg1 underlined, then print arg2 normally.
 '\"
 '\" RCS: @(#) $Id: man.macros,v 1.4 2000/08/25 06:18:32 ericm Exp $
 '\"
 '\"	# Set up traps and other miscellaneous stuff for Tcl/Tk man pages.
 .if t .wh -1.3i ^B
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 '\"	# Start an argument description
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 .ie !"\\$4"" .TP \\$4
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 .   ie !"\\$2"" .TP \\n()Cu
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 .\}
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 \&\\$1	\\fI\\$2\\fP	(\\$3)
 .\".b
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 ..
 .AS Tcl_Interp Tcl_CreateInterp in/out
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 .el \}\
 \h'-1.5n'\L'|\\n(^yu-1v'\h'\\n(^lu+3n'\L'\\n(^tu+1v-\\n(^yu'\l'|0u-1.5n\(ul'
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 .LP
 See the \\fBoptions\\fR manual entry for details on the standard options.
 ..
 '\"	# OP - start of full description for a single option
 .de OP
 .LP
 .nf
 .ta 4c
 Command-Line Name:	\\fB\\$1\\fR
 Database Name:	\\fB\\$2\\fR
 Database Class:	\\fB\\$3\\fR
 .fi
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 \\$1\l'|0\(ul'\\$2
 ..
 .TH focus n 4.0 Tk "Tk Built-In Commands"
 .BS
 '\" Note:  do not modify the .SH NAME line immediately below!
 .SH NAME
 focus \- Manage the input focus
 .SH SYNOPSIS
 \fBfocus\fR
 .sp
 \fBfocus \fIwindow\fR
 .sp
 \fBfocus \fIoption\fR ?\fIarg arg ...\fR?
 .BE

 .SH DESCRIPTION
 .PP
 The \fBfocus\fR command is used to manage the Tk input focus.
 At any given time, one window on each display is designated as
 the \fIfocus window\fR;  any key press or key release events for the
 display are sent to that window.
 It is normally up to the window manager to redirect the focus among the
 top-level windows of a display.  For example, some window managers
 automatically set the input focus to a top-level window whenever
 the mouse enters it;  others redirect the input focus only when
 the user clicks on a window.
 Usually the window manager will set the focus
 only to top-level windows, leaving it up to the application to
 redirect the focus among the children of the top-level.
 .PP
 Tk remembers one focus window for each top-level (the most recent
 descendant of that top-level to receive the focus);  when the window
 manager gives the focus
 to a top-level, Tk automatically redirects it to the remembered
 window.  Within a top-level Tk uses an \fIexplicit\fR focus model
 by default.  Moving the mouse within a top-level does not normally
 change the focus;  the focus changes only when a widget
 decides explicitly to claim the focus (e.g., because of a button
 click), or when the user types a key such as Tab that moves the
 focus.
 .PP
 The Tcl procedure \fBtk_focusFollowsMouse\fR may be invoked to
 create an \fIimplicit\fR focus model:  it reconfigures Tk so that
 the focus is set to a window whenever the mouse enters it.
 The Tcl procedures \fBtk_focusNext\fR and \fBtk_focusPrev\fR
 implement a focus order among the windows of a top-level;  they
 are used in the default bindings for Tab and Shift-Tab, among other
 things.
 .PP
 The \fBfocus\fR command can take any of the following forms:
 .TP
 \fBfocus\fR
 Returns the path name of the focus window on the display containing
 the application's main window,  or an empty string if no window in
 this application has the focus on that display.   Note:  it is
 better to specify the display explicitly using \fB\-displayof\fR
 (see below) so that the code will work in applications using multiple
 displays.
 .TP
 \fBfocus \fIwindow\fR
 If the application currently has the input focus on \fIwindow\fR's
 display, this command resets the input focus for \fIwindow\fR's display
 to \fIwindow\fR and returns an empty string.
 If the application doesn't currently have the  input focus on
 \fIwindow\fR's display, \fIwindow\fR will be remembered as the focus
 for its top-level;  the next time the focus arrives at the top-level,
 Tk will redirect it to \fIwindow\fR.
 If \fIwindow\fR is an empty string then the command does nothing.
 .TP
 \fBfocus \-displayof\fR \fIwindow\fR
 Returns the name of the focus window on the display containing \fIwindow\fR.
 If the focus window for \fIwindow\fR's display isn't in this
 application, the return value is an empty string.
 .TP
 \fBfocus \-force \fIwindow\fR
 Sets the focus of \fIwindow\fR's display to \fIwindow\fR, even if
 the application doesn't currently have the input focus for the display.
 This command should be used sparingly, if at all.
 In normal usage, an application should not claim the focus for
 itself;  instead, it should wait for the window manager to give it
 the focus.
 If \fIwindow\fR is an empty string then the command does nothing.
 .TP
 \fBfocus \-lastfor\fR \fIwindow\fR
 Returns the name of the most recent window to have the input focus
 among all the windows in the same top-level as \fIwindow\fR.
 If no window in that top-level has ever had the input focus, or
 if the most recent focus window has been deleted, then the name
 of the top-level is returned.  The return value is the window that
 will receive the input focus the next time the window manager gives
 the focus to the top-level.

 .SH "QUIRKS"
 .PP
 When an internal window receives the input focus, Tk doesn't actually
 set the X focus to that window;  as far as X is concerned, the focus
 will stay on the top-level window containing the window with the focus.
 However, Tk generates FocusIn and FocusOut events just as if the X
 focus were on the internal window.   This approach gets around a
 number of problems that would occur if the X focus were actually moved;
 the fact that the X focus is on the top-level is invisible unless
 you use C code to query the X server directly.

 .SH KEYWORDS
 events, focus, keyboard, top-level, window manager
	'\"
	'\" Copyright (c) 1990-1994 The Regents of the University of California.
	'\" Copyright (c) 1994-1996 Sun Microsystems, Inc.
	'\"
	'\" See the file "license.terms" for information on usage and redistribution
	'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
	'\"
	'\" RCS: @(#) $Id: focus.n,v 1.2 1998/09/14 18:22:56 stanton Exp $
	'\"
	'\" The definitions below are for supplemental macros used in Tcl/Tk
	'\" manual entries.
	'\"
	'\" .AP type name in/out ?indent?
	'\" Start paragraph describing an argument to a library procedure.
	'\" type is type of argument (int, etc.), in/out is either "in", "out",
	'\" or "in/out" to describe whether procedure reads or modifies arg,
	'\" and indent is equivalent to second arg of .IP (shouldn't ever be
	'\" needed; use .AS below instead)
	'\"
	'\" .AS ?type? ?name?
	'\" Give maximum sizes of arguments for setting tab stops. Type and
	'\" name are examples of largest possible arguments that will be passed
	'\" to .AP later. If args are omitted, default tab stops are used.
	'\"
	'\" .BS
	'\" Start box enclosure. From here until next .BE, everything will be
	'\" enclosed in one large box.
	'\"
	'\" .BE
	'\" End of box enclosure.
	'\"
	'\" .CS
	'\" Begin code excerpt.
	'\"
	'\" .CE
	'\" End code excerpt.
	'\"
	'\" .VS ?version? ?br?
	'\" Begin vertical sidebar, for use in marking newly-changed parts
	'\" of man pages. The first argument is ignored and used for recording
	'\" the version when the .VS was added, so that the sidebars can be
	'\" found and removed when they reach a certain age. If another argument
	'\" is present, then a line break is forced before starting the sidebar.
	'\"
	'\" .VE
	'\" End of vertical sidebar.
	'\"
	'\" .DS
	'\" Begin an indented unfilled display.
	'\"
	'\" .DE
	'\" End of indented unfilled display.
	'\"
	'\" .SO
	'\" Start of list of standard options for a Tk widget. The
	'\" options follow on successive lines, in four columns separated
	'\" by tabs.
	'\"
	'\" .SE
	'\" End of list of standard options for a Tk widget.
	'\"
	'\" .OP cmdName dbName dbClass
	'\" Start of description of a specific option. cmdName gives the
	'\" option's name as specified in the class command, dbName gives
	'\" the option's name in the option database, and dbClass gives
	'\" the option's class in the option database.
	'\"
	'\" .UL arg1 arg2
	'\" Print arg1 underlined, then print arg2 normally.
	'\"
	'\" RCS: @(#) $Id: man.macros,v 1.4 2000/08/25 06:18:32 ericm Exp $
	'\"
	'\" # Set up traps and other miscellaneous stuff for Tcl/Tk man pages.
	.if t .wh -1.3i ^B
	.nr ^l \n(.l
	.ad b
	'\" # Start an argument description
	.de AP
	.ie !"\\$4"" .TP \\$4
	.el \{\
	. ie !"\\$2"" .TP \\n()Cu
	. el .TP 15
	.\}
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	..
	'\" # define tabbing values for .AP
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	.nr )A 10n
	.if !"\\$1"" .nr )A \\w'\\$1'u+3n
	.nr )B \\n()Au+15n
	.\"
	.if !"\\$2"" .nr )B \\w'\\$2'u+\\n()Au+3n
	.nr )C \\n()Bu+\\w'(in/out)'u+2n
	..
	.AS Tcl_Interp Tcl_CreateInterp in/out
	'\" # BS - start boxed text
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	.mk ^y
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	'\" # BE - end boxed text (draw box now)
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	.ie n \l'\\n(^lu\(ul'
	.el \{\
	.\" Draw four-sided box normally, but don't draw top of
	.\" box if the box started on an earlier page.
	.ie !\\n(^b-1 \{\
	\h'-1.5n'\L'\|\\n(^yu-1v'\l'\\n(^lu+3n\(ul'\L'\\n(^tu+1v-\\n(^yu'\l'\|0u-1.5n\(ul'
	.\}
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	..
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	.\}
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	'\" # box/sidebar if in box/sidebar mode, then invoked standard
	'\" # page bottom macro.
	.de ^B
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	'ti 0
	'nf
	.mk ^t
	.if \\n(^b \{\
	.\" Draw three-sided box if this is the box's first page,
	.\" draw two sides but no top otherwise.
	.ie !\\n(^b-1 \h'-1.5n'\L'\|\\n(^yu-1v'\l'\\n(^lu+3n\(ul'\L'\\n(^tu+1v-\\n(^yu'\h'\|0u'\c
	.el \h'-1.5n'\L'\|\\n(^yu-1v'\h'\\n(^lu+3n'\L'\\n(^tu+1v-\\n(^yu'\h'\|0u'\c
	.\}
	.if \\n(^v \{\
	.nr ^x \\n(^tu+1v-\\n(^Yu
	\kx\h'-\\nxu'\h'\|\\n(^lu+3n'\ky\L'-\\n(^xu'\v'\\n(^xu'\h'\|0u'\c
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	.if \\n(^b \{\
	.mk ^y
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	.if \\n(^v \{\
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	..
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	..
	'\" # DE - end display
	.de DE
	.fi
	.RE
	.sp
	..
	'\" # SO - start of list of standard options
	.de SO
	.SH "STANDARD OPTIONS"
	.LP
	.nf
	.ta 5.5c 11c
	.ft B
	..
	'\" # SE - end of list of standard options
	.de SE
	.fi
	.ft R
	.LP
	See the \\fBoptions\\fR manual entry for details on the standard options.
	..
	'\" # OP - start of full description for a single option
	.de OP
	.LP
	.nf
	.ta 4c
	Command-Line Name: \\fB\\$1\\fR
	Database Name: \\fB\\$2\\fR
	Database Class: \\fB\\$3\\fR
	.fi
	.IP
	..
	'\" # CS - begin code excerpt
	.de CS
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	.nf
	.ta .25i .5i .75i 1i
	..
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	.de CE
	.fi
	.RE
	..
	.de UL
	\\$1\l'\|0\(ul'\\$2
	..
	.TH focus n 4.0 Tk "Tk Built-In Commands"
	.BS
	'\" Note: do not modify the .SH NAME line immediately below!
	.SH NAME
	focus \- Manage the input focus
	.SH SYNOPSIS
	\fBfocus\fR
	.sp
	\fBfocus \fIwindow\fR
	.sp
	\fBfocus \fIoption\fR ?\fIarg arg ...\fR?
	.BE

	.SH DESCRIPTION
	.PP
	The \fBfocus\fR command is used to manage the Tk input focus.
	At any given time, one window on each display is designated as
	the \fIfocus window\fR; any key press or key release events for the
	display are sent to that window.
	It is normally up to the window manager to redirect the focus among the
	top-level windows of a display. For example, some window managers
	automatically set the input focus to a top-level window whenever
	the mouse enters it; others redirect the input focus only when
	the user clicks on a window.
	Usually the window manager will set the focus
	only to top-level windows, leaving it up to the application to
	redirect the focus among the children of the top-level.
	.PP
	Tk remembers one focus window for each top-level (the most recent
	descendant of that top-level to receive the focus); when the window
	manager gives the focus
	to a top-level, Tk automatically redirects it to the remembered
	window. Within a top-level Tk uses an \fIexplicit\fR focus model
	by default. Moving the mouse within a top-level does not normally
	change the focus; the focus changes only when a widget
	decides explicitly to claim the focus (e.g., because of a button
	click), or when the user types a key such as Tab that moves the
	focus.
	.PP
	The Tcl procedure \fBtk_focusFollowsMouse\fR may be invoked to
	create an \fIimplicit\fR focus model: it reconfigures Tk so that
	the focus is set to a window whenever the mouse enters it.
	The Tcl procedures \fBtk_focusNext\fR and \fBtk_focusPrev\fR
	implement a focus order among the windows of a top-level; they
	are used in the default bindings for Tab and Shift-Tab, among other
	things.
	.PP
	The \fBfocus\fR command can take any of the following forms:
	.TP
	\fBfocus\fR
	Returns the path name of the focus window on the display containing
	the application's main window, or an empty string if no window in
	this application has the focus on that display. Note: it is
	better to specify the display explicitly using \fB\-displayof\fR
	(see below) so that the code will work in applications using multiple
	displays.
	.TP
	\fBfocus \fIwindow\fR
	If the application currently has the input focus on \fIwindow\fR's
	display, this command resets the input focus for \fIwindow\fR's display
	to \fIwindow\fR and returns an empty string.
	If the application doesn't currently have the input focus on
	\fIwindow\fR's display, \fIwindow\fR will be remembered as the focus
	for its top-level; the next time the focus arrives at the top-level,
	Tk will redirect it to \fIwindow\fR.
	If \fIwindow\fR is an empty string then the command does nothing.
	.TP
	\fBfocus \-displayof\fR \fIwindow\fR
	Returns the name of the focus window on the display containing \fIwindow\fR.
	If the focus window for \fIwindow\fR's display isn't in this
	application, the return value is an empty string.
	.TP
	\fBfocus \-force \fIwindow\fR
	Sets the focus of \fIwindow\fR's display to \fIwindow\fR, even if
	the application doesn't currently have the input focus for the display.
	This command should be used sparingly, if at all.
	In normal usage, an application should not claim the focus for
	itself; instead, it should wait for the window manager to give it
	the focus.
	If \fIwindow\fR is an empty string then the command does nothing.
	.TP
	\fBfocus \-lastfor\fR \fIwindow\fR
	Returns the name of the most recent window to have the input focus
	among all the windows in the same top-level as \fIwindow\fR.
	If no window in that top-level has ever had the input focus, or
	if the most recent focus window has been deleted, then the name
	of the top-level is returned. The return value is the window that
	will receive the input focus the next time the window manager gives
	the focus to the top-level.

	.SH "QUIRKS"
	.PP
	When an internal window receives the input focus, Tk doesn't actually
	set the X focus to that window; as far as X is concerned, the focus
	will stay on the top-level window containing the window with the focus.
	However, Tk generates FocusIn and FocusOut events just as if the X
	focus were on the internal window. This approach gets around a
	number of problems that would occur if the X focus were actually moved;
	the fact that the X focus is on the top-level is invisible unless
	you use C code to query the X server directly.

	.SH KEYWORDS
	events, focus, keyboard, top-level, window manager