NAME
XtAddGrab, XtRemoveGrab - redirect user input to a modal widget
SYNTAX
void
XtAddGrab(Widget w, Boolean exclusive, Boolean
spring_loaded);
void
XtRemoveGrab(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