XtAddGrab(3) XT FUNCTIONS XtAddGrab(3)
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 InterfaceX Version 11 libXt 1.1.5 XtAddGrab(3)
