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'\" Copyright (c) 1994-1996 Sun Microsystems, Inc.

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'\" RCS: @(#) $Id: bindtags.n,v 1.1.1.1 2002-01-16 10:25:48 markom Exp $

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.so man.macros

.TH bindtags n 4.0 Tk "Tk Built-In Commands"

.BS

'\" Note:  do not modify the .SH NAME line immediately below!

.SH NAME

bindtags \- Determine which bindings apply to a window, and order of evaluation

.SH SYNOPSIS

\fBbindtags \fIwindow \fR?\fItagList\fR?

.BE

.SH DESCRIPTION

.PP

When a binding is created with the \fBbind\fR command, it is

associated either with a particular window such as \fB.a.b.c\fR,

a class name such as \fBButton\fR, the keyword \fBall\fR, or any

other string.

All of these forms are called \fIbinding tags\fR.

Each window contains a list of binding tags that determine how

events are processed for the window.

When an event occurs in a window, it is applied to each of the

window's tags in order:  for each tag, the most specific binding

that matches the given tag and event is executed.

See the \fBbind\fR command for more information on the matching

process.

.PP

By default, each window has four binding tags consisting of the

name of the window, the window's class name, the name of the window's

nearest toplevel ancestor, and \fBall\fR, in that order.

Toplevel windows have only three tags by default, since the toplevel

name is the same as that of the window.

The \fBbindtags\fR command allows the binding tags for a window to be

read and modified.

.PP

If \fBbindtags\fR is invoked with only one argument, then the

current set of binding tags for \fIwindow\fR is returned as a list.

If the \fItagList\fR argument is specified to \fBbindtags\fR,

then it must be a proper list; the tags for \fIwindow\fR are changed

to the elements of the list.

The elements of \fItagList\fR may be arbitrary strings;  however,

any tag starting with a dot is treated as the name of a window;  if

no window by that name exists at the time an event is processed,

then the tag is ignored for that event.

The order of the elements in \fItagList\fR determines the order in

which binding scripts are executed in response to events.

For example, the command

.CS

\fBbindtags .b {all . Button .b}\fR

.CE

reverses the order in which binding scripts will be evaluated for

a button named \fB.b\fR so that \fBall\fR bindings are invoked

first, following by bindings for \fB.b\fR's toplevel (``.''), followed by

class bindings, followed by bindings for \fB.b\fR.

If \fItagList\fR is an empty list then the binding tags for \fIwindow\fR

are returned to the default state described above.

.PP

The \fBbindtags\fR command may be used to introduce arbitrary

additional binding tags for a window, or to remove standard tags.

For example, the command

.CS

\fBbindtags .b {.b TrickyButton . all}\fR

.CE

replaces the \fBButton\fR tag for \fB.b\fR with \fBTrickyButton\fR.

This means that the default widget bindings for buttons, which are

associated with the \fBButton\fR tag, will no longer apply to \fB.b\fR,

but any bindings associated with \fBTrickyButton\fR (perhaps some

new button behavior) will apply.

.SH "SEE ALSO"

bind

.SH KEYWORDS

binding, event, tag