I asked this question back in >December 2012 and just stumbled across the answer when I was looking at monitoring when a titlebar text changes. Funny how things seem so simple when you know how. #include <ScrollbarConstants.au3> #include <WinAPISys.au3> Global $hEventProc = DllCallbackRegister('_EventProc', 'none', 'ptr;dword;hwnd;long;long;dword;dword') Global $hEventHook = _WinAPI_SetWinEventHook($EVENT_OBJECT_VALUECHANGE, $EVENT_OBJECT_VALUECHANGE, DllCallbackGetPtr($hEventP