non-rendering fonts

[moseley@hank.org]

Is there a way to debug fontconfig's font selection?

I did a dist-upgrade on my Sid laptop this morning and upon restarting 
icewm its fonts had vanished.  It only happens with one icewm theme, so 
it would seem to be a font selection problem.  But I can't figure out 
what changed to cause the problem.  The problem was discussed on the 
icewm mailing list[1] and there's a bug against the icewm package[2].

I assume the X experts know how to debug problems like this.  Fonts are 
a common topic on debian-user, and there's a lot of HOWTOs and setup 
examples, but I have not found anything that helps me debug problems.

It's my basic lack of understanding of X, of course.  Do any of you know 
of a good font _debugging_ howto?  

For example, in icewm it seems like this font family:

 -artwiz-snap-regular-r-normal-sans-10-*-*-*-*-*-*-*-*"

is the problem.  I probably don't have that font installed, but I assume 
previously there was a font substitution happening that worked, and 
now there's a different font substitution happening that doesn't 
display.  But that's just my guess.

Is there a way to debug that font selection process?  My limited
understanding is the application uses fontconfig to find a font, then X
for rendering that font.

I think it would be very helpful for me (in debugging problems like 
this) to be able to watch the font selection process for an application.  
For example, I would like to watch what font icewm is requesting, and 
what actually gets selected and rendered.

Is there a way to do that?


[1] http://sourceforge.net/mailarchive/forum.php?thread_id=3305608&forum_id=5805
[2] http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=214677

And a similar request to fontconfig list some time back:

http://mail.fontconfig.org/pipermail/fontconfig/2003-July/000508.html

-- 
Bill Moseley
moseley@hank.org