Updates a specified rectangle or region in the client area.
BOOL RedrawWindow(
   LPCRECT lpRectUpdate = NULL,
   HRGN hRgnUpdate = NULL,
   UINT flags = RDW_INVALIDATE | RDW_UPDATENOW | RDW_ERASE 
); throw() 
Remarks
See RedrawWindow in the Windows SDK.
Example
//The following example attaches an HWND to the CWindow object and 
//calls CWindow::RedrawWindow() to update the entire window using the 
//default arguments
CWindow myWindow;
myWindow.Attach(hWnd);
BOOL bRedrawn = myWindow.RedrawWindow();
Requirements
Header: atlwin.h