After some operation app window contains 'old' drawings.
If I drag my window outside of screen bounds, it repaints and 'old' drawings
So I consider my window needs only repainting.
Whatever I try - UpdateWindow, RedrawWindow - nothing happens. How to
repaint window client region 'right now' ?
I'm not sure about RedrawWindow - what exactly parameters I should use ?
InvalidateRect (hwnd, NULL, TRUE) ;