AccessibleObjectFromWindow(hWnd, (uint) OBJID.WINDOW, ref guid, ref accessible);

The AccessibleObjectFromWindow function retrieves the address of the specified interface to the object associated with the given window.

    internal static extern int AccessibleObjectFromWindow(

    Private Declare Function AccessibleObjectFromWindow Lib "oleacc" (ByVal Hwnd As Int32, _

    Private Declare Function AccessibleObjectFromWindow Lib "oleacc" (ByVal Hwnd As Int32, _

    Dim aaVal As Int32 = AccessibleObjectFromWindow(hWnd, ID, IID_IAcce, varChild)

    int retVal = AccessibleObjectFromWindow(hwnd, (uint)OBJID.WINDOW, ref guid, ref obj);

    /// Applications never send this message directly. It is sent only by Active Accessibility in response to calls to AccessibleObjectFromPoint, AccessibleObjectFromEvent, or AccessibleObjectFromWindow. However, server applications handle this message.

    '''Active Accessibility sends the WM_GETOBJECT message to obtain information about an accessible object contained in a server application. Applications never send this message directly. It is sent only by Active Accessibility in response to calls to AccessibleObjectFromPoint AccessibleObjectFromEvent or AccessibleObjectFromWindow. However server applications handle this message.