Steps to reproduce:
1. Create an tk2dUIItem, assign a target to "Send Message"
2. Assign an event in either On Down, On Up, On Click, On Release (Assuming I'm assigning an event in On Down)
3. Save scene (It works here, the event has been serialized during Save Scene)
4. Now change the event that we previously assigned to On Down, to some other events.
5. Save scene
6. Reload the scene, u will notice the tk2dUIItem still holding the first event that we assigned to it instead of the second event.
Please fix.
It must have caused by new Multi-Scene editing in Unity 5.3.4