Calculates the required size of the window rectangle, based on the desired size of the client rectangle
#include <WinAPISysWin.au3>
_WinAPI_AdjustWindowRectEx ( ByRef $tRECT, $iStyle [, $iExStyle = 0 [, $bMenu = False]] )
| $tRECT | $tagRECT structure that contains the coordinates of the desired client area. This structure must be created before function call. |
| $iStyle | The window style of the window whose required size is to be calculated. Note that you cannot specify the $WS_OVERLAPPED style. |
| $iExStyle | [optional] The extended window style of the window whose required size is to be calculated. |
| $bMenu | [optional] Specifies whether the window has a menu, valid values: True - The window has a menu. False - The window does not has a menu (Default). |
| Success: | True. |
| Failure: | False, call _WinAPI_GetLastError() to get extended error information. |
Search AdjustWindowRectEx in MSDN Library.