GRAB(9) GRAB(9)
NAME
grab - Confine pointer and keyboard events to a window sub-
tree
SYNOPSIS
grab what ?arg arg ...?
DESCRIPTION
This command implements simple pointer grabbing for Tk.
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 window's tree, button presses and releases and mouse
motion events are reported to window, and window entry and
window exit events are ignored. The grab subtree ``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.
A 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 grabs the window manager will not receive
pointer events either (which means that if the grab is not
released the whole GUI will freeze, so be careful!).
The grab command can take any of the following forms:
grab release window
Releases the grab on window if there is one, otherwise
does nothing. Returns an empty string.
grab set window
If a grab was already in effect for this application on
window's display then it is automatically released. If
there is already a grab on window then the command does
nothing. Returns an empty string.
grab ifunset window
Same as grab set except that window is only grabbed if
there is no other grab currently in effect.
grab status window
GRAB(9) GRAB(9)
Returns none if no grab is currently set on window, or
window if it has the grab.
BUGS
The current application-exclusive nature of grab is a prob-
lem which will be adressed in the future.