Yes, this has been tested (at least)..
The other time I tried this hack, I failed (Hmm..Was new.. )..So here it is..

Screens: None

Download: here

Enjoy, even thought it's small .

Nice hack, I think TheX has a similar hack on his forum so he may be able to tell us if the code is right and your unsure.

My suggestion: add a dropdown of colors, then check if the color is in that list. (then for example, they can't use black on a black background... and maybe it's possible to exploit it if you don't do what I suggested, but I don't think so)

Maybe I can make a simple script if it's in the range of a dark color, say dark brown on black, then it won't be available in the list?