Retrieves a handle of a display device context for the client area a window
#include <WinAPIGdiDC.au3>
_WinAPI_GetDC ( $hWnd )
| $hWnd | Handle of window | 
| Success: | The device context for the given window's client area | 
| Failure: | 0 | 
After painting with a common device context, the _WinAPI_ReleaseDC() function must be called to release the DC
_WinAPI_DeleteDC, _WinAPI_ReleaseDC
Search GetDC in MSDN Library.