XtAddGrab(3Xt) X Version 11 (Release 3) XtAddGrab(3Xt)
NAME
XtAddGrab, XtRemoveGrab - 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.
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
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XtAddGrab(3Xt) X Version 11 (Release 3) XtAddGrab(3Xt)
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
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