This is how wxpropgrid draws them... I don't see why this is a problem?
The idea is probably to be less distracting than the real valuable information in the members of the category.
Old post, but an on going dilemma...
The labels must contrast against any background color for accessibility purposes for those whom endure visual impairments. I have photosensitive eyes and am red-green color blind, but will program for the challenges regardless. I am not jumping your case oBFusCATed just enlightening anyone who reads this thread in the future.