The Layered window demonstrates transparent windows available under NT 5+.
Layered window requires at least Windows 2000.
Layered window, (2003-02-18)
This program was written as an experiment with Layered Windows as supported by the Windows API.
To use transparency, we override the default processing of the WM_PAINT message, setting the WS_EX_LAYERED extended style and calling SetLayeredWindowAttributes() to specify an alpha value.
device = BeginPaint(window, &ps); SetWindowLongPtr(window, GWL_EXSTYLE, GetWindowLongPtr(window, GWL_EXSTYLE) | WS_EX_LAYERED); SetLayeredWindowAttributes(window, 0, alpha, LWA_ALPHA); EndPaint(window, &ps);
The application uses a slider bar to control the transparency value. Don't forget to call InitCommonControls() before trying to use the slide.