UpdateWindow()

Hi,

I´m having a little problem to redraw my created window. So if anyone could give me a hint on how to use UpdateWindow() or RedrawWindow(), I would be very happy.Also I´m trying to draw this window on a round area, should it work the way I figured or? Included is my constructor:

CMainFrame::CMainFrame()
{
CRect r;
r.SetRect(100,100,200,200);
CRgn m_wndRgn;
Create(NULL, "Simple MFC App",
WS_POPUP,
r, NULL, NULL, 0, NULL );
GetWindowRect(r);
m_wndRgn.CreateEllipticRgn (r.left,r.top,
r.Width(),r.Height());
SetWindowRgn(m_wndRgn,TRUE);
ModifyStyle(0, WS_SYSMENU, 0);
ModifyStyleEx (WS_EX_CLIENTEDGE, 0, 0);
m_bMouseDown = FALSE;
UpdateWindow(); // ?? doesn´t work, why?

}