+++ /dev/null
-'\"
-'\" Copyright (c) 1992 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.
-'\"
-.TH grab n "" Tk "Tk Built-In Commands"
-.so man.macros
-.BS
-'\" Note: do not modify the .SH NAME line immediately below!
-.SH NAME
-grab \- Confine pointer and keyboard events to a window sub-tree
-.SH SYNOPSIS
-\fBgrab \fR?\fB\-global\fR? \fIwindow\fR
-.sp
-\fBgrab \fIoption \fR?\fIarg arg \fR...?
-.BE
-.SH DESCRIPTION
-.PP
-This command implements simple pointer and keyboard grabs for Tk.
-Tk's grabs are different than the grabs
-described in the Xlib documentation.
-When a grab is set for a particular window, Tk restricts all pointer
-events to the grab window and its descendants in Tk's window hierarchy.
-Whenever the pointer is within the grab window's subtree, the pointer
-will behave exactly the same as if there had been no grab at all
-and all events will be reported in the normal fashion.
-When the pointer is outside \fIwindow\fR's tree, button presses and
-releases and
-mouse motion events are reported to \fIwindow\fR, and window entry
-and window exit events are ignored. The grab subtree
-.QW owns
-the pointer:
-windows outside the grab subtree will be visible on the screen
-but they will be insensitive until the grab is released.
-The tree of windows underneath the grab window can include top-level
-windows, in which case all of those top-level windows
-and their descendants will continue to receive mouse events
-during the grab.
-.PP
-Two forms of grabs are possible: local and global.
-A local grab affects only the grabbing application: events will
-be reported to other applications as if the grab had never occurred.
-Grabs are local by default.
-A global grab locks out all applications on the screen,
-so that only the given subtree of the grabbing application will be
-sensitive to pointer events (mouse button presses, mouse button releases,
-pointer motions, window entries, and window exits).
-During global grabs the window manager will not receive pointer
-events either.
-.PP
-During local grabs, keyboard events (key presses and key releases)
-are delivered as usual: the window
-manager controls which application receives keyboard events, and
-if they are sent to any window in the grabbing application then they are
-redirected to the focus window.
-During a global grab Tk grabs the keyboard so that all keyboard events
-are always sent to the grabbing application.
-The \fBfocus\fR command is still used to determine which window in the
-application receives the keyboard events.
-The keyboard grab is released when the grab is released.
-.PP
-Grabs apply to particular displays. If an application has windows
-on multiple displays then it can establish a separate grab on each
-display.
-The grab on a particular display affects only the windows on
-that display.
-It is possible for different applications on a single display to have
-simultaneous local grabs, but only one application can have a global
-grab on a given display at once.
-.PP
-The \fBgrab\fR command can take any of the following forms:
-.TP
-\fBgrab \fR?\fB\-global\fR? \fIwindow\fR
-Same as \fBgrab set\fR, described below.
-.TP
-\fBgrab current \fR?\fIwindow\fR?
-If \fIwindow\fR is specified, returns the name of the current grab
-window in this application for \fIwindow\fR's display, or an empty
-string if there is no such window.
-If \fIwindow\fR is omitted, the command returns a list whose elements
-are all of the windows grabbed by this application for all displays,
-or an empty string if the application has no grabs.
-.TP
-\fBgrab release \fIwindow\fR
-Releases the grab on \fIwindow\fR if there is one, otherwise does
-nothing. Returns an empty string.
-.TP
-\fBgrab set \fR?\fB\-global\fR? \fIwindow\fR
-Sets a grab on \fIwindow\fR. If \fB\-global\fR is specified then the
-grab is global, otherwise it is local.
-If a grab was already in effect for this application on
-\fIwindow\fR's display then it is automatically released.
-If there is already a grab on \fIwindow\fR and it has the same
-global/local form as the requested grab, then the command
-does nothing. Returns an empty string.
-.TP
-\fBgrab status \fIwindow\fR
-Returns \fBnone\fR if no grab is currently set on \fIwindow\fR,
-\fBlocal\fR if a local grab is set on \fIwindow\fR, and
-\fBglobal\fR if a global grab is set.
-.SH WARNING
-.PP
-It is very easy to use global grabs to render a display completely
-unusable (e.g. by setting a grab on a widget which does not respond to
-events and not providing any mechanism for releasing the grab). Take
-\fIextreme\fR care when using them!
-.SH BUGS
-.PP
-It took an incredibly complex and gross implementation to produce
-the simple grab effect described above.
-Given the current implementation, it is not safe for applications
-to use the Xlib grab facilities at all except through the Tk grab
-procedures.
-If applications try to manipulate X's grab mechanisms directly,
-things will probably break.
-.PP
-If a single process is managing several different Tk applications,
-only one of those applications can have a local grab for a given
-display at any given time. If the applications are in different
-processes, this restriction does not exist.
-.SH EXAMPLE
-.PP
-Set a grab so that only one button may be clicked out of a group. The
-other buttons are unresponsive to the mouse until the middle button is
-clicked.
-.CS
-pack [button .b1 \-text "Click me! #1" \-command {destroy .b1}]
-pack [button .b2 \-text "Click me! #2" \-command {destroy .b2}]
-pack [button .b3 \-text "Click me! #3" \-command {destroy .b3}]
-\fBgrab\fR .b2
-.CE
-.SH "SEE ALSO"
-busy(n)
-.SH KEYWORDS
-grab, keyboard events, pointer events, window
-'\" Local Variables:
-'\" mode: nroff
-'\" End:
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