Free form

Is it ossible to have free window shapes?

I think of following :
I got an transparent png, and now i want to only paint the area
the png is nontransparent. When i do it in the normal way the background color of the window is painted or if i manually workout WM_ERASEBKGND it is transparent but if i move a window over the transparent window the image of the window stays there.

I can provide links to the binary if it isnt undertandable.

Use regions to define the shape and SetWindowRgn to apply it to your window. There's an example in this thread that may be of interest. Search this board and google for other examples.