   [Win32 C++] Transparent windows alike Yahoo Widgets
  I've been trying for the past few days to do a true per-pixel alpha blended non-rectangular window, using only C++ and the Win32 API..I've been looking all around the web and found that I (may) use the UpdateLayeredWindow(...) function, but that for the alpha the colors must be pre-calculated... havent really figured how that works out, here's why:I've tried to do things manually - get the desktop's DC, do per-pixel alpha blending "manually" using a grayscale mask image. The problem is that if I move my window, I get itself drawn on the desktop, so I get the "mirror within mirror" effect ...How does that pre-calculated alpha blending work to use with UpdateLayeredWindow()??   