Hi there. Well lets jump right in... I have build a program that displays an alpha blended Dialog in windows using UpdateLayeredWindow. Everything worked until yesterday when I had to change my Desktop's color depth to 16bit. But that's not really the problem. I found out pretty quick that I used a compatible bitmap for updating which, since I now only have 16 bits, doesn't contain alpha information. I realised that I had to use a DIB with 32bit to store the Graphics updates and assign it to a DC. dib = CreateDIBSection(....); HDC dc = CreateCompatibleDC(NULL); SelectObject(dc, dib); This works. But calling UpdateLayeredWindow() with the dc into which the dib is selected the call just fails and GetLastError() returns 0. O_o It doesn't work either in 16bit nor in 32bit video mode. But It worked before with a device dependent bitmap, only in 32bit mode. Please help me... this is really frustrating. Am I doing something fundamentally wrong? Thanks in advance.

Actually I got it working now.
I just exchanged all MFC calls and classes with their respective GDI counterparts.
Seems like MFC doesn't like DIBs... hm.