Hello, hope somebody can help me...

I want to create a VB6 UserControl, which has a Transparency property. I do copy the rectangle underneath the UC into a backbuffer DC. Draw my controls into that backbuffer and move the content to the UCs DC via BitBlt.
This works fine until Aero comes into the game! - In this case the UCs parent form is black. This results in a black background on my UC, which features a DIBSection.
I did already introduce a transparent color (because text is also black), which I can remove via GDI+ and ColorMap, when blitting to the destination DC. This works also fine, until I use the DrawThemeTextEx API, which is drawing an alpha blended glow effect. This effect changes my transparent color a little, so that I am not able any more to remove it from my back buffer.
I did try to use a 32bit bitmap for my back buffer, but here I was not able to draw controls via the DrawThemeBackground API (but maybe I did something wrong - am am very new to this kind of programming).

Has somebody any idea, how I can solve my problem?
Maybe a 32bit DC, which can be used like a normal DC, created with the CreateCompatibleDC API?