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authordkf <donal.k.fellows@manchester.ac.uk>2004-06-21 21:19:41 (GMT)
committerdkf <donal.k.fellows@manchester.ac.uk>2004-06-21 21:19:41 (GMT)
commitbc696a02fb5559b0525ce407d2d77ccd970f61d0 (patch)
treec98885b0d63433297618b12908079fa42faa3996 /doc
parent87cf64cd1df28e50b055448199a7aa3b83828e95 (diff)
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Added example and warning about global grabs
Diffstat (limited to 'doc')
-rw-r--r--doc/grab.n18
1 files changed, 16 insertions, 2 deletions
diff --git a/doc/grab.n b/doc/grab.n
index 887ae66..a47c13d 100644
--- a/doc/grab.n
+++ b/doc/grab.n
@@ -5,7 +5,7 @@
'\" See the file "license.terms" for information on usage and redistribution
'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
'\"
-'\" RCS: @(#) $Id: grab.n,v 1.2 1998/09/14 18:22:56 stanton Exp $
+'\" RCS: @(#) $Id: grab.n,v 1.3 2004/06/21 21:19:41 dkf Exp $
'\"
.so man.macros
.TH grab n "" Tk "Tk Built-In Commands"
@@ -102,7 +102,11 @@ does nothing. Returns an empty string.
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
+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
@@ -117,6 +121,16 @@ 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 doesn't exist.
+.SH EXAMPLE
+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}]
+grab .b2
+.CE
.SH KEYWORDS
grab, keyboard events, pointer events, window