void InvalidateRgn( CRgn* pRgn, BOOL bErase = TRUE );
Parameters
pRgn
A pointer to a CRgn object that identifies the display region of the OLE object to invalidate, in client coordinates of the containing window. If this parameter is NULL, the extent is the entire object.
bErase
Specifies whether the background within the invalidated region is to be erased. If TRUE, the background is erased. If FALSE, the background remains unchanged.
Remarks
Call this function to invalidate the container window's client area within the given region. This can be used to redraw windowless controls within the container. The invalidated region, along with all other areas in the update region, is marked for painting when the next WM_PAINT message is sent.
If bErase is TRUE for any part of the update region, the background in the entire region, not just in the given part, is erased.