Create tools for testing GUIs

[mgalloy]

It would be useful to be able to insert an event handler (an EVENT_FUNC?) into the top-level base which would record each event in a file. Then a separate event player would be needed to play back the events recorded previously. This would need a mechanism to handle widget identifiers in the events that would not necessarily be the same in the playback (maybe by using UNAMEs?).