Adds a region to the specified window's update region
_WinAPI_InvalidateRgn ( $hWnd [, $hRgn = 0 [, $bErase = True]] )
|$hWnd||Handle to the window with an update region that is to be modified.|
|$hRgn||[optional] Handle to the region to be added to the update region. The region is assumed to have client coordinates.
If this parameter is 0, the entire client area is added to the update region.
|$bErase||[optional] Specifies whether the background within the update region is to be erased when the update region is processed, valid values:
True - The background is erased (Default).
False - The background remains unchanged.
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