The colors .configuration files contain sections "[Colors:Header]" and "[Colors:Header][Inactive]". The former is configurable in the kcm_colors but the latter is not.
Kind of like the reverse issue of Bug 433059. Adding support for this in kcoloscehemeeditor should hopefully not be too hard though. Wanna take a crack at it?
*** Bug 468261 has been marked as a duplicate of this bug. ***