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.