Windows NT redisplay bug or feature?

It seems to me that both 21.4.3 and 21.5.1 do not redraw toolbars and scrollbars until mouse pointer enters the frame. To reproduce: minimize frame and then restore it. On my win2000 SP1 toolbars and scrollbars do not redraw until I move mouse pointer inside the frame. No screenshots are available because when i press PrintScreen button xemacs redraws and appeares on the screenshot in all its beauty :)) It is in no way annoying but *stable* xemacs shoud not behave like this, IMHO. Nick.