Can you explain in detail why is this causing you a problem?
Mostly performance, because it is generating a frame repaint even if the frame isn't dirty. I have a widget set with a kind of CSS box model and I use the frame to do the margin, border and padding.
Window message spy shows that WM_SYNCPAINT isn't being generated. The problem happens when the window became dirty (something is over it and needs redraw when it's gone) and not from resizing. I'm thinking in forgetting BeginPaint() and getting the DC by myself and validating the region by "hand".