WinAPI BitBlt Desktop to GUI

#include <WindowsConstants.au3>
#include <WinAPI.au3>

$hWnd = GUICreate("Test", 400, 400)
GUISetState()

$hDC_Window = _WinAPI_GetDC($hWnd)
$hDC_Desktop = _WinAPI_GetDC(0)

_WinAPI_BitBlt($hDC_Window, 0, 0, 400, 400, $hDC_Desktop, 0, 0, $SRCCOPY)

While GUIGetMsg() <> -3
WEnd

_WinAPI_ReleaseDC($hWnd, $hDC_Window)
_WinAPI_ReleaseDC(0, $hDC_Desktop)