Subject: Re: FVWM: xscreensaver colormap bug?

From: "Paul D. Smith" <[email-masked]>
Date: 25 Aug 2000 18:24:06 -0400

%% On 18 Jun 1998 16:50:56 -0400
%% Regarding FVWM: xscreensaver colormap bug?; I wrote:

Yes, more than two years have gone by.

I just noticed this on the XScreenSaver web site, and I wonder if it
applies to FVWM?

> The installColormap option doesn't work very well with the twm (1)
> window manager and its descendants.
>
> There is a race condition between the screensaver and this window
> manager, which can result in the screensaver's colormap not getting
> installed properly, meaning the graphics hacks will appear in
> essentially random colors. (If the screen goes white instead of black,
> this is probably why.)
>
> The mwm (1) and olwm (1) window managers don't have this problem. The
> race condition exists because X (really, ICCCM) does not provide a way
> for an OverrideRedirect window to have its own colormap, short of
> grabbing the server (which is neither a good idea, nor really possible
> with the current design.) What happens is that, as soon as xscreensaver
> installs its colormap, twm responds to the resultant ColormapNotify
> event by re-instaling the default colormap. Apparently, twm doesn't
> always do this; it seems to do it regularly if the screensaver is
> activated from a menu item, but seems to not do it if the screensaver
> comes on of its own volition, or is activated from another console.
>
> Attention, window manager authors! 
>                                                           
> You should only call XInstallColormap (3) in response to user
> events. That is, it is appropriate to install a colormap in response to
> FocusIn, FocusOut, EnterNotify, and LeaveNotify events; but it is not
> appropriate to call it in response to ColormapNotify events. If you
> install colormaps in response to application actions as well as in
> response to user actions, then you create the situation where it is
> impossible for override-redirect applications (such as xscreensaver) to
> display their windows in the proper colors.

http://www.jwz.org/xscreensaver/man1.html#12

What do you think?

There is still a bug #5 open about this against FVWM.

-- 
-------------------------------------------------------------------------------
 Paul D. Smith <[email-masked]>         Network Management Development
 "Please remain calm...I may be mad, but I am a professional." --Mad Scientist
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---

From: Dan Espen <[email-masked]>
Date: Mon, 28 Aug 2000 15:58:16 -0400

> Yes, more than two years have gone by.

Time flies when you are having fun.

> > essentially random colors. (If the screen goes white instead of black,
...
> There is still a bug #5 open about this against FVWM.

I tested this just now.  I first allocated all my colors, then modified
my XScreensaver setup to install colormaps.

I tried  about 10 times and each   time, the hack  ran with  the right
colormap.

A long  time ago I reported  that fvwm DID  have  this problem.  While
trying  to solve  it, I  realized  that  I was  using  xli  and xv  as
substitutes for the  hacks that come with  xscreensaver.  For this  to
work correctly,  the hack has to use  the root colormap and both those
programs use the default colormap.

I don't think fvwm has a problem with xscreensaver.

--
Dan Espen
444 Hoes Lane  Room RRC 1C-214           E-mail: [email-masked]
Piscataway, NJ 08854                     Phone: (732) 699-5570
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