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XtAddGrab(3Xt)
X11R6
NAME
  XtAddGrab, XtRemoveGrab - redirect user input to a modal widget

SYNOPSIS
  void XtAddGrab(w, exclusive, spring_loaded)
	  Widget w;
	  Boolean exclusive;
	  Boolean spring_loaded;

  void XtRemoveGrab(w)
	  Widget w;

ARGUMENTS
  exclusive
      Specifies whether user events should be dispatched exclusively to this
      widget or also to previous widgets in the cascade.

  spring_loaded
      Specifies whether this widget was popped up because the user pressed a
      pointer button.

  w   Specifies the widget to add to or remove from the modal cascade.

DESCRIPTION
  The XtAddGrab function appends the widget (and associated parameters) to
  the modal cascade and checks that exclusive is True if spring_loaded is
  True. If these are not True, XtAddGrab generates an error.

  The modal cascade is used by XtDispatchEvent when it tries to dispatch a
  user event. When at least one modal widget is in the widget cascade,
  XtDispatchEvent first determines if the event should be delivered. It
  starts at the most recent cascade entry and follows the cascade up to and
  including the most recent cascade entry added with the exclusive parameter
  True.

  This subset of the modal cascade along with all descendants of these
  widgets comprise the active subset. User events that occur outside the
  widgets in this subset are ignored or remapped. Modal menus with submenus
  generally add a submenu widget to the cascade with exclusive False.  Modal
  dialog boxes that need to restrict user input to the most deeply nested
  dialog box add a subdialog widget to the cascade with exclusive True. User
  events that occur within the active subset are delivered to the appropriate
  widget, which is usually a child or further descendant of the modal widget.

  Regardless of where on the screen they occur, remap events are always
  delivered to the most recent widget in the active subset of the cascade
  that has spring_loaded True, if any such widget exists.

  The XtRemoveGrab function removes widgets from the modal cascade starting
  at the most recent widget up to and including the specified widget. It
  issues an error if the specified widget is not on the modal cascade.

SEE ALSO
  X Toolkit Intrinsics -- C Language Interface

  Xlib -- C Language X Interface

Index for Section 3Xt

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