'\"
'\" Copyright (c) 1997 Maorong Zou
'\" 
.TH EZ_AddEventHandler 3 "" EZWGL "EZWGL Functions"
.BS
.SH NAME
EZ_AddEventHandler,EZ_RemoveEventHandler,
EZ_RemoveAllEventHandlers  \- register/remove event handlers associated to a widget

.SH SYNOPSIS
.nf
.B #include <EZ.h>
.sp
.BI "void EZ_AddEventHandler( EZ_Widget" *widget ",
.BI "        EZ_EventHandler " handler ", void "*clientdata ", int " location)
.BI "void EZ_AddEventHandler00( EZ_Widget" *widget ",
.BI "        EZ_EventHandler " handler ", void "*clientdata ", int " location)
.BI "void EZ_AddEventHandlerAll( EZ_Widget" *widget ",
.BI "        EZ_EventHandler " handler ", void "*clientdata ", int " location)
.BI "void EZ_RemoveEventHandler( EZ_Widget" *widget ",
.BI "                         EZ_EventHandler " handler ", void "*clientdata)
.BI "void EZ_RemoveEventHandler00( EZ_Widget" *widget ",
.BI "                         EZ_EventHandler " handler ", void "*clientdata)
.BI "void EZ_RemoveAllEventHandlers( EZ_Widget " *widget )
.BI "void EZ_RemoveAllEventHandlers00( EZ_Widget " *widget )


.SH ARGUMENTS
\fIwidget\fR  Specifies an EZ widget.
.sp
\fIhandler\fR  Specifies an event handler.
.sp
\fIclientdata\fR  Specifies a clientdata to be passed to the
event handler.
.sp
\fIlocation\fR  Specifies when the event handler is to be called
relative to other previously registered handlers
.sp
.SH DESCRIPTION
.PP
An event handler is a procedure of the following prototype:
.sp
.nf
void(*handler)(void *object, void *data, int etype, XEvent *event)
.fi
.PP
\fBEZ_AddEventHandler\fR registers an event handler to a widget. If
\fIlocation\fR is 0, the event handler will be put in front
of all previously registered event handlers. If \fIlocation\fR is
1, the event handler will be inserted at the end of all
previousely registered event handlers.
.PP
For composite widget, \fBEZ_AddEventHandler\fR inserts the event
handler to the most relevent internal widget. To add an event handler
to the toplevel frame of a composite widget, use \fBEZ_AddEventHandler00\fR.
.PP
\fBEZ_AddEventHandlerAll\fR registers an event handler to widget and
all its descendants.
.PP
\fBEZ_RemoveEventHandler\fR deletes an event handler. The specified
event handler will be deleted only if both the procedure and
the client data match.
.PP
For composite widget, \fBEZ_RemoveEventHandler\fR removes the specified event
handler from the most relevent internal widget. To remove an event handler
from a composite widget, use \fBEZ_RemoveEventHandler00\fR.

.PP
\fBEZ_RemoveAllEventHandlers\fR deletes all event handlers registered
to a widget.
.PP
For composite widget, \fBEZ_RemoveAllEventHandlers\fR removes all event
handlers from the most relevent internal widget. To remove all event handlers
registered to the toplevel frame of a composite widget,
use \fBEZ_RemoveAllEventHandlers00\fR.

.SH "SEE ALSO"
EZ_AddWidgetCallBack(3)
.br