I am still trying to nail down theme creation. Because each game should have different theme creating new themas easily with treegui should be top priority (even more sow then the layout of controls because game normally dont have that many buttons.)
There is what i cam up with. Draw the gui texture in photoshop gimp what ever then use your favorite 3d program (no matter what but i used blender)
To lay out the boxes around the texture controls:
start blender pick your image texture as background: 
use blenders project from view to map right on to the texture
uv map squares over every control you want …
this is blender so the thing is in 3d even though we will not use the 3d view but compute from the 2d texture layout view.
the final this is that every thing should be named according to function consult the documintation on what that will and might be.
texture used:
Then just export as egg and use that as theme! That is much better idea then going through inscape or my own custom tool because
#1 you dont have to learn some thing new!
#2 any 3d tool that can export egg (or format that panda3d can load .x,3ds…) can now be used as a theme designer by sticking to naming conventions!
#3 the 3d editor was not exaclty build for this function but i am sure it has way more sort cuts and tools for this then any thing i could build!
I think using theme designer in this way is the best idea? What do you think?