Retrieves the dimensions of the bounding rectangle of the specified window
#include <WinAPISysWin.au3>
_WinAPI_GetWindowRect ( $hWnd )
| $hWnd | Handle of the window |
| Success: | $tagRECT structure that receives the screen coordinates |
| Failure: | Sets the @error flag to non-zero, call _WinAPI_GetLastError() to get extended error information |
Search GetWindowRect in MSDN Library.