[lnpedro]

Perdonad pero la funcion del API windows.GetClientRect( hWnd, ARect );no esta diseñada para capturar la imagen de la pantalla solo rasigna a ARect las dimensiones de la zona cliente de la ventana con el hWnd especificado.
encontrado en la ayuda de delphi 7.

The GetClientRect function retrieves the coordinates of a window's client area. The client coordinates specify the upper-left and lower-right corners of the client area. Because client coordinates are relative to the upper-left corner of a window's client area, the coordinates of the upper-left corner are (0,0).

BOOL GetClientRect(

HWND hWnd, // handle of window
LPRECT lpRect // address of structure for client coordinates
);


Parameters

hWnd

Identifies the window whose client coordinates are to be retrieved.

lpRect

Points to a RECT structure that receives the client coordinates. The left and top members are zero. The right and bottom members contain the width and height of the window.



Return Values

If the function succeeds, the return value is nonzero.
If the function fails, the return value is zero. To get extended error information, call GetLastError.