Changing background colors

[lrcgtk red4est com]

I'm working on a project at work, and writing the user interface in gtk. 

The specifications for the program include that it look like the previous
generation program. Therefore, the software has to have black background.

Gtk seems to REALLY  want grey backgrounds. I've tried playing around with 
my .gtkrc file, but can only get some of the fields to turn black. 
A lot of times I can get the foreground color to change, but not the 
background color.

I've seen hints that some widgets (like labels) don't have a background
color and that you have to change the background on the parent.
However, I can't seem to find anything that documents which characteristics:
fg, bg, base, text are active on which widgets. Since I've now spent about 
two weeks on something that should have taken me about two hours, I'm
in a bit of trouble, and would greatly appreciate some pointers to 
documentation.

I tried doing a test program of just some of the plotting features
that I'm trying to implement, and while gtk_gc_set_foreground() works
 just fine, gtk_gc_set_background has no apparent effect.

Thanks
   Larry Colen
   lrc red4est com