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From: rthomson@mesa.dsd.es.com (Rich Thomson)
Newsgroups: comp.windows.x
Subject: Re: Xt Intrinsics, extensions, and event handlers
Keywords: Xt,X extensions,multibuffering,nonmaskable event handlers
Message-ID: <1991May30.035234.7581@dsd.es.com>
Date: 30 May 91 03:52:34 GMT
References: <1224@mdavcr.UUCP>
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In article <1224@mdavcr.UUCP>
	furr@mdavcr.UUCP (Steven Furr) writes:
>I would like to know if there is any way of providing Xt Event handlers
>to handle events that come from X extensions.  The event type of these
>events is not known until the extension is initialized, and the event
>cannot be selected with XSelectInput.
>
 [...]
>
>The problem is that Xt doesn't seem capable of dispatching any nonmaskable
>events to the event handler other than GraphicsExpose, NoExpose,
>MappingNotify, SelectionClear, SelectionRequest, SelectionNotify, and
>ClientMessage (as per p. 225 of O'Reilly vol. 4).
>
>Shouldn't event types outside the range of the X standard protocol be
>considered nonmaskable events by Xt? (i.e. those that get assigned to
>extension events)
>
>Since this appears not to be the case is there any possibility that this
>will change with X11.R5?

I have been discussing this with Ralph Swick at MIT.  There was some
talk in this newsgroup earlier about dealing with such problems for
the input extension.

The problem is that the Intrinsics are generally extension-illiterate,
unlike Xlib.  I think it was initially thought that most extensions
wouldn't generate events, but this isn't a very good assumption.  E&S'
custom PEX picking extension generates events, the X Input Extension
(in the R5 release) generates events, etc.

In general, I think not only this problem with event handlers needs to
be addressed, but the larger problem of event management in general.
Most of the work is getting the Translation Manager to be literate of
extensions.  A workable minimum is some version of the TM that is at
least literate of the Input Extension for R5.  The problem is a sticky
one indeed.

Unfortunately, I can't comment (yet) on your proposed change to the
sample implementation because I haven't the time to learn the
internals of the Toolkit.  Maybe in the summer (yeah, right! :).

						-- Rich
-- 
  ``Read my MIPS -- no new VAXes!!'' -- George Bush after sniffing freon
	    Disclaimer: I speak for myself, except as noted.
UUCP: ...!uunet!dsd.es.com!rthomson		Rich Thomson
ARPA: rthomson@dsd.es.com			PEXt Programmer