I'm not entirely sure this hasn't been suggested before, or maybe isn't already hidden somewhere in the GUI and I'm just somehow overlooking it. Hopefully neither of the above for my own sake.
Anyhow, I could definitely see the benefit from a search window that allows you to search for global/private variables and lists instances of where they are altered and referenced. It would be displayed as they normally are on event sheets, but would also show its path and so on.
Just a small suggestion.