mozilla/butter — pull request #1109 by secretrobotron (2012-10-10 20:32:11+00:00)
Title: [t2464] Better TrackEvent update error detection and recovery

1. Created src/core/observer to give classes ability to notify subscribers of events (synchronous).
2. Created src/strings to start holding Butter-wide strings.
3. Removed independent setErrorState, updateTrackEvent* from editors.
4. Added centralized updateTrackEventSafe to TrackEventEditor.
5. Rerouted TrackEvent update mechanisms to use updateTrackEventSafe in editors.
6. Added trackevent update subscriber to src/core/track to reject an update if overlap occurs.