Tk Source Code

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.TH busy n "" Tk "Tk Built-In Commands"
.so man.macros
.BS
'\" Note:  do not modify the .SH NAME line immediately below!
.SH NAME
busy \- confine pointer events to a window sub-tree
.SH SYNOPSIS
\fBtk busy\fR \fIwindow \fR?\fIoptions\fR?
.sp
\fBtk busy hold\fR \fIwindow \fR?\fIoptions\fR?
.sp
\fBtk busy configure \fIwindow\fR ?\fIoption value\fR?...
.sp
\fBtk busy forget\fR \fIwindow \fR?\fIwindow \fR?...
.sp
\fBtk busy current\fR ?\fIpattern\fR?
.sp
\fBtk busy status \fIwindow\fR
.BE
.SH DESCRIPTION
.PP
The \fBtk busy\fR command provides a simple means to block pointer events from
Tk widgets, while overriding the widget's cursor with a configurable busy
cursor. Note this command does not prevent keyboard events from being sent to
the widgets made busy.
.SH INTRODUCTION
.PP
There are many times in applications where you want to temporarily restrict
what actions the user can take. For example, an application could have a
.QW Run
button that when pressed causes some processing to occur. However, while the
application is busy processing, you probably don't want the user to be

The \fBtk busy\fR command lets you make Tk widgets busy. This means that user
interactions such as button clicks, moving the mouse, typing at the keyboard,
etc.\0are ignored by the widget. You can set a special cursor (like a watch)
that overrides the widget's normal cursor, providing feedback that the
application (widget) is temporarily busy.
.PP
When a widget is made busy, the widget and all of its descendants will ignore
pointer events. It's easy to make an entire panel of widgets busy. You can
simply make the toplevel widget (such as
.QW . )
busy. This is easier and far much more efficient than recursively traversing
the widget hierarchy, disabling each widget and re-configuring its cursor.
.PP
Often, the \fBtk busy\fR command can be used instead of Tk's \fBgrab\fR
command. Unlike \fBgrab\fR which restricts all user interactions to one
widget, with the \fBtk busy\fR command you can have more than one widget

.PP
Mapping and unmapping busy windows generates Enter/Leave events for all
widgets they cover. Please note this if you are tracking Enter/Leave events in
widgets.
.SS "KEYBOARD EVENTS"
.PP
When a widget is made busy, the widget is prevented from gaining the keyboard
focus by a user clicking on it by the busy window. But if the widget already had
focus, it still may receive keyboard events. The widget can also still receive
focus through keyboard traversal. To prevent this, you must move
focus to another window and make sure the focus can not go back to the widgets
made busy (e.g. but restricting focus to a cancel button).
.PP
.CS
pack [frame .frame]
pack [text .frame.text]
\fBtk busy\fR hold .frame
pack [button .cancel -text "Cancel" -command exit]
focus .cancel
bind .cancel <Tab> {break}
bind .cancel <Shift-Tab> {break}
update
.CE
.PP
The above example moves the focus from .frame immediately after invoking the
\fBhold\fR so that no keyboard events will be sent to \fB.frame\fR or any of
its descendants. It also makes sure it's not possible to leave button
\fB.cancel\fR using the keyboard.
.SH PORTABILITY
.PP
Note that the \fBtk busy\fR command does not currently have any effect on OSX
when Tk is built using Aqua support.
.SH "SEE ALSO"
grab(n)
.SH KEYWORDS
busy, keyboard events, pointer events, window
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