How to create a window with transparent background?

Question

Is possible/how to create a window without background or set her background transparent?

Another way than using a layered window , because controls will be loaded into the window.

My goal is to create a GUI with rounded borders, for that, I will load a picture as the background.

Answer 1

A layered window with the LWA_COLORKEY attribute is problematic if you want (Windows standard) child controls because there is no perfect color to pick as the transparent color.

However, layered windows have another mode; UpdateLayeredWindow . This function is perfect if you have an image (with alpha transparency) you want to use as the background. Just make sure the bitmap is pre-multiplied 32-bit ARGB before selecting it into the DC.

If for some crazy reason you can't use layered windows, the older option is SetWindowRgn .

The newer option is DirectComposition but I'm not sure if you are forced to set the layered style on the window.