I think it also has to do with how well the gpu supports various opengl versions. I simply cannot get dark breeze to display the kmenu, etc properly on my old laptop, but on my less old PC, with a reasonable and fairly new graphics card, it works properly once I set the compositor to glx/ opengl 3.1. (both already have blur and contrast on)
Ooookay, I take that back. It will work on the ole laptop, doing what you did. What I thought was a check mark in the Blur and Background Contrast were really a diagonal "half-box". Once I clicked each to make them fully checked, it works. Go figure. Thank you for helping me notice this
Now the real question is what does this half-selected box means, darnit!