GNUstep on FreeBSD problems

[Wolfgang Lux]

Hello!

I recently installed FreeBSD and also attempted to use GNUstep on  
FreeBSD. Building GNUstep-startup from svn worked fine with one minor  
exception [1]. However, when starting any GNUstep program I got  
XBadMatch errors on the console and the windows and menus were all  
completely white. After finding this helpful hint
  http://lists.gnu.org/archive/html/discuss-gnustep/2008-04/ 
msg00081.html
from Andrew Ruder to set the environment variable  
XLIB_SKIP_ARGB_VISUALS everything seems to works fine.

This weekend, I found some time to take a closer look at the problem.  
Apparently, it is caused by an inconsistent handling of X visuals in  
x11/context.m and in the libart backend. The latter in method  
setupDrawInfo of class ARTContext simply uses the first DirectColor  
or TrueColor visual returned by XGetVisualInfo. The code in x11/ 
context.m, on the other hand, is more involved. The function  
bestContext looks at all TrueColor visuals returned by XGetVisualInfo  
and chooses a visual with depth 24 or higher if available. On my  
FreeBSD installation this leads to a problem because the Xorg  
server's default visual uses 16 bits, but the server also offers a 32- 
bit visual (unless XLIB_SKIP_ARGB_VISUALS is set). Thus, every X  
window will use a 32-bit drawable but the graphic primitives of the  
libart backend attempt to send 16-bit images to that drawable causing  
the XBadMatch errors.

Of course, a quick and dirty fix would be to copy the code from  
bestContext to setupDrawInfo (or vice versa), but I feel that  
XGServer's context and ARTContext should not be using different  
visual in the first place. Unfortunately, I haven't dig far enough  
into the sources so far in order to understand the relation between  
the libart and cairo backends on one side and the common X11 code on  
the other side, but maybe someone more knowledgeable than me (Fred?)  
has some idea how to fix this.

Incidentally, XGScreenContext's code includes some logic to force  
XGServerWindow into using a particular visual under control of the  
user default NSDefaultVisual, but unfortunately the call to the  
relevant method (_getXDefaults) is commented out in - 
initForDisplay:screen:. Is there any reason for this?

Wolfgang

[1] Given the recent discussions on libffi vs. ffcall, I decided to  
build GNUstep with libffi. Since FreeBSD is considered a generic  
platform by GNUstep-startup the default is to use ffcall. I therefore  
invoked InstallGNUstep with the --ffi=libffi option but this did not  
work because the gsflags shell function resets the GS_FFI variable to  
the default for the chosen platform. The following patch is a  
workaround, but it looks like a hack to me; there should be no need  
to set GS_FFI twice.

startup.patch
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