wine users - Oct 2007 - GLSL registry entry

I currently have the registry entry 
HKEY_CURRENT_USER\Software\Wine\Direct3d\UseGLSL set to enabled, but I'm 
getting behavior as if it weren't set - and when I change the setting, 
for example to "disabled," there's no change in behavior. I know
for
sure the path is right, because I also have VideoMemorySize set and that 
works.

Is there some way to directly test GLSL outside of wine, to see if it's 
available?