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Re: [XForms] XForms failure after upgrading to Fedora 19

From: Jens Thoms Toerring
Subject: Re: [XForms] XForms failure after upgrading to Fedora 19
Date: Tue, 14 Jan 2014 21:41:01 +0100
User-agent: Mutt/1.5.21 (2010-09-15)

Hi Russ,

On Tue, Jan 14, 2014 at 03:09:09PM -0500, R P Herrold wrote:
> On Tue, 14 Jan 2014, Jens Thoms Toerring wrote:
> > Now I've got to figure out what that event is supposed to
> > be good for and catch it within XForms internally instead
> > of passing it on to the program...
> There is a witches brew of such signalling going on -- perhaps 
> more sanely, catching what one understand and considers well 
> formed, and simply passing through what one does not consume, 
> is a sounder strategy?

The problem is that there's no-one it could be passed on to.
Or, to be precise, that's just the approach taken already:
if some XEvent arrives that's not intended for one of the
windows XForms opened the only reasonable assumption is
that the program using the library has opened a window of
its own and thus will take care of XEvents for it. Thus
all XEvents not for windows managed by XForms are "passed
on" - onto an internal queue of XEvents. The programmer
should then set up a callback for these events. If he
doesn't do that they get signalled by fl_do_forms() and
friends returning a kind of dummy object (and the pro-
gram then can inspect the contents of the internal event
queue with fl_XNextEvent() etc.).

A pronlem arises when an XEvent is received for a window
that neither XForms nor the program opened. XForms passes
it on but if there's no taker than we're in trouble. And
that's precisely what happens here: nothing opened the win-
dow this strange XEvent is intended for, so there's nothing
taking resonsibility for it - and it ends up as an unexpec-
ted return from fl_do_forms().

> The 'freedesktop.org' folks have any number of signalling
> approaches not contained in traditional  X11.

I very much hope that they don't make it a common feature
to send XEvents for windows to programs that don't opened
these windows. Otherwise we're going to be in some trouble
since the whole library is written under the assumption
that this won't happen.

So I hope that this is some kind of bug and we can get rid
of the "fix" again in the forseable future. But at the moment
it's the only solution I can think of to make it possible again
to reliably run programs using XForms under newer versions of
                         Best regards, Jens
  \   Jens Thoms Toerring  ________      address@hidden
   \_______________________________      http://toerring.de

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