proper way to implement KDE or WMaker-like multiple backgrounds

[Eric Shattow]

i've switched to using OpenBox3, from a long history of WindowMaker 
use.  there's a couple features i really miss, one i know can be 
implemented in user-space, and the other which i can't decide if it 
belongs in the windowmanager or not.

i'm talking about having a unique root wallpaper for each workspace. KDE 
supports this with elegance, and GNOME does not. i run GNOME for 
whatever reasons i run it. would then, adding an OpenBox3 configuration 
option to run an external program when switching to a different 
workspace, would that be acceptable? is it within the scope of the 
OpenBox3 project to provide this kind of functionality?

for efficiency and proper functionality, where should the implementation 
of unique root wallpaper-per-workspace be?  the WM? the desktop 
environment? external commands triggered by WM configuration? an 
independent daemon that spies on X11 and waits for the workspace to change?

i've heard all the arguments for "oh just use KDE" and "why do you run 
GNOME with all of the GNOME desktop flair turned off? you suck! use 
twm!"  i have RAM to burn, and i'm happy with how easily customizable 
the keybindings for OpenBox3 are.   i still miss the pretty backgrounds.

opinions to hear, patches to try, and all advice welcomed

- Eric Shattow