.\" $Xorg: XtAddGrab.man,v 1.3 2000/08/17 19:41:57 cpqbld Exp $
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.\" $XFree86: xc/doc/man/Xt/XtAddGrab.man,v 1.2 2001/01/27 18:20:23 dawes Exp $
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.ds xW X Toolkit Athena Widgets \- C Language Interface
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.ds xC Inter-Client Communication Conventions Manual
.ds Rn 3
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.hw XtAdd-Grab wid-get
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.TH XtAddGrab __libmansuffix__ __xorgversion__ "XT FUNCTIONS"
.SH NAME
XtAddGrab, XtRemoveGrab \- redirect user input to a modal widget
.SH SYNTAX
.HP
void XtAddGrab(Widget \fIw\fP, Boolean \fIexclusive\fP, Boolean
\fIspring_loaded\fP); 
.HP
void XtRemoveGrab(Widget \fIw\fP); 
.SH ARGUMENTS
.IP \fIexclusive\fP 1i
Specifies whether user events should be dispatched exclusively to this widget 
or also to previous widgets in the cascade.
.IP \fIspring_loaded\fP 1i
Specifies whether this widget was popped up because the user pressed
a pointer button.
.ds Wi to add to or remove from the modal cascade
.IP \fIw\fP 1i
Specifies the widget \*(Wi.
.SH DESCRIPTION
The
.ZN XtAddGrab
function appends the widget (and associated parameters) to the modal cascade
and checks that exclusive is 
.ZN True 
if spring_loaded is 
.ZN True .
If these are not 
.ZN True , 
.ZN XtAddGrab
generates an error.
.LP
The modal cascade is used by
.ZN XtDispatchEvent
when it tries to dispatch a user event.
When at least one modal widget is in the widget cascade, 
.ZN 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
.ZN True .
.LP
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 
.ZN 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 
.ZN 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.
.LP
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 
.ZN True ,
if any such widget exists.
.LP
The
.ZN 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.
.SH "SEE ALSO"
.br
\fI\*(xT\fP
.br
\fI\*(xL\fP