UpdateWindow( hWnd )-> <nil>
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 PARAMETER:

  <hWnd>        Is the handle that identifies the window to be updated



 DESCRIPTION:

  The UpdateWindow function updates the client area of the given window by
  sending it a WM_PAINT message, which forces it to be repainted if the
  update region for the window is not empty. Otherwise, no message is sent. 
  The function sends this message directly to the window procedure of
  the given window, bypassing the application queue.


 SOURCE:

  SOURCE\WINAPI\WNDUPDAT.C