libxfcegui4's xinerama wrapper

[Brian J. Tarricone]

this is mainly a question for olivier, but if anyone else can help...

i was looking into xfdesktop xinerama support, but the libxfcegui4 
interfaces don't seem to be all that useful.  for example, when i'm 
creating a new backdrop image, i have the screen number. from the 
number, i need the width and height of the screen so i can size the 
image properly.  however, MyDisplay{Width,Height}() requires an x and y 
coordinate, which it looks like are global coords, which it uses to 
figure out which head the coordinates belong to, and then get the screen 
size.  but, 1) i don't have coordinates, and 2) i already know which 
head i want.

i really want to use the xinerama wrapper, since it means i don't have 
to add more compile-time conditionals, and i get the xinerama emulation 
for free to test with.  is there some way i can use this in a sane 
manner that's useful to me?

	-brian

p.s. note also that MyDisplay{Width,Height}() is not very smart when 
xinerama isn't enabled.  if GDK_USE_SCREEN is set, you'll get incorrect 
results if there are multiple non-xinerama screens that are of 
different sizes.