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 XtAddGrab(Xt)     X Version 11 (Release 5) 6 January 1993      XtAddGrab(Xt)


 Name

    XtAddGrab - redirect user input to a modal widget

 Syntax


    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.

    springloaded
              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 cas-
              cade.

 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 parame-
    ter 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 sub-
    menus 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