How to detect mouse click in external window?

[qwert]

I have a script that is called from an external application in order to perform some housekeeping functions -- but it has to know when the user clicks inside of an external window. I've tried this simple method below, but the click action is never detected. Is there a mouse detection step specifically for this? (BTW, as the first action in the script, I retrieve the handle of the external window -- but I haven't found a way to use it.)

While 1
   $Msg = GUIGetMsg()
   Select
      Case $Msg = $GUI_EVENT_CLOSE
         Exit
      Case $Msg = $GUI_EVENT_PRIMARYDOWN
        MsgBox(32, "Click Detected", "", 1)
   EndSelect
Wend

Thanks in advance for any help.

[SpookMeister]

#include <Misc.au3>
HotKeySet("{ESC}", "_Quit")
$dll = DllOpen("user32.dll")
While 1
    Sleep(10)
    If _IsPressed(01, $dll) Then
        $pos = MouseGetPos()
        MsgBox(0, "_IsPressed", "Mouse Left button" & @CRLF & "Mouse x,y:" & $pos[0] & "," & $pos[1])
    EndIf
WEnd
Func _Quit()
    DllClose($dll)
    Exit
EndFunc   ;==>_Quit

[qwert]

That worked perfectly in my utility -- and it's a very clear example of direct dll access.

Thanks very much.

[SpookMeister]

Note:

http://msdn2.microsoft.com/en-us/library/ms645540.aspx