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From: scott@graft.Berkeley.EDU (Scott Silvey)
Newsgroups: comp.windows.x
Subject: Re: Possible Event Handler Bug
Message-ID: <1991Jan14.222932.773@agate.berkeley.edu>
Date: 14 Jan 91 22:29:32 GMT
References: <9101122029.AA08824@kiwi.lgc.com> <9101122032.AA28066@expire.lcs.mit.edu>
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Reply-To: scott@xcf.berkeley.edu
Organization: UC Berkeley Experimental Computing Facility
Lines: 26

rws@expo.lcs.mit.EDU (Bob Scheifler) writes:
|>>     I think if you call XChangeActivePointerGrab in your button press
|>>     event handler with a mask that includes PointerMotionMask and
|>>     ButtonReleaseMask, your problem will go away (but I haven't actually
|>>     run the test).
|> 
|> I have.  To do it right, you should also specify the time from the event in
|> the call:
|> 	...
|> 	XtAddEventHandler(canvas, PointerMotionMask, FALSE, motion, NULL);
|> 	XChangeActivePointerGrab(XtDisplay(canvas),
|> 				 PointerMotionMask|ButtonReleaseMask,
|> 				 None, evt->xbutton.time);

Thank you gentlemen for your prompt replies.  This indeed corrects the problem.

This seems a rather obscure fix to me (although I see why it is necessary).
  Is it an oversight that XtAddEventHandler doesn't already make this call?
  Or was it a design decision to omit it because XtAddEventHandler would then
  have to do specialized work based on the event mask it was called with?

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