I took only a superficial look:
You're leaking hrgn (never deleting it). Actually, there's no need at all for regions -- why not simply using FillRect? If that doesn't solve it, please repost and I'll dig more into it.
Side note:
Note that same effect (pale yellow background, isn't it?) can be achieved by ommitting WM_PAINT altoghether and specifying WC%hbrBackground to a pale yellow brush. The process goes like this:
- When something is to be redrawn, WM_ERASEBKGND is first sent, provided that WC%hbrBackground is non-NULL.
- By default (DefWindowProc), entire background is filled with WC%hbrBackground
- Immediately after that, WM_PAINT is sent, and you can draw your image here. Portions that you don't draw remains in background color. If you don't handle WM_PAINT, nothing is drawn over the already filled background.
So, if you cover entire window area in WM_PAINT (using FillRect, BitBlt or similar), you should set hbrBackground to NULL, so that erasing doesn't take place twice. That tends to reduce flicker during resizing as well.
Jugoslav
