Trasparency Problems

Hi to all the member of Autoit Community
I have searched around the forum but i don't have found a solution

I want to add to every active windows a trasparency, but not to all the windows but only a specific region
For now i have make this:

 
#include <GuiconstantsEx.au3>
#include <WindowsConstants.au3>
#include <WinAPI.au3>
 
HotKeySet("{ESC}", "On_Exit")
 
;~ Local $GUI = WinGetHandle("[ACTIVE]", "")
Local $GUI = GUICreate("trans", 300, 400, -1, -1, -1, $WS_EX_LAYERED)
_WinAPI_SetLayeredWindowAttributes($GUI, 0x010101, 150)
GUISetState()
 
While 1
 Switch GUIGetMsg()
  Case $GUI_EVENT_CLOSE
   ExitLoop
 EndSwitch
WEnd
 
Func On_Exit()
 Exit
EndFunc   ;==>On_Exit

work for the GUI but not for the active external windows.
Some help?

Thanks