panorama for dual head displays: howto?

Can somebody tell me where the WM source code for wmsetbg controls how 
backgrounds are shown on dual head displays?  I have an Nvidia dual 
video card and have been happy that WM shows the same image on both 
monitors.  That's different from Gnome's Nautilus/Metacity, which 
stretches one background across the two monitors. Nvidia does not use 
Xinerama. Rather, it has something they call Twinview which makes the 
dual head appear as one big 2056x1024 monitor.  But the WM backgrounds 
don't cooperate--the 2 monitors are still backgrounded separately.  But 
I can drag windows across the heads and the Gnome workspace pager thing 
does show the double wide monitors as single workspaces.

Lately I've found some wide images and want to re-configure WM to 
stretch across dual monitors.  I feel sure this is possible because 
there was a brief time when WM did stretch the background across the 
dual displays.  It was about 2 years ago, I think.  I've been looking 
through the WM source code, but I can't find the right part.


-- 
Paul E. Johnson                       email: [email protected]
Dept. of Political Science            http://lark.cc.ku.edu/~pauljohn
1541 Lilac Lane, Rm 504
University of Kansas                  Office: (785) 864-9086
Lawrence, Kansas 66044-3177           FAX: (785) 864-5700
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