I just think backwards compatibility should be maintained when there are acceptable (admittedly, not perfect) workarounds available.

Perhaps this could be another event that supports the undocumented "me:" prefix so that you can catch the event triggering yourself.

Code:
on me:*:open:?:{ 
  ; I opened the window.
}
on *:open:?:{
  ; Someone/something else caused the window to open.
}