winxp style background color problem

I have a program with the famous winxp style. My program uses a tab control and when different tabs are chosen, the correct window is shown on top of the dialog.

But because i use a maindialog with childwindows, the background collors of the controls are wrong. Is there an easy way to set the background color of a control or is there an other solution? Im using win32 API and c.

I already tried SetBkColor but this just doesnt work :(

EDIT I just found some info on this board about how to do this.... never mind this post.