XtAddGrab(3Xt) XtAddGrab(3Xt)
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.
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XtAddGrab(3Xt) XtAddGrab(3Xt)
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 Programming Manual
Xlib Programming Manual
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