* Enhanced mixins, replaced cursor handling with more features.

* Cleanup and fixes to interactive classes.

Mouse over/out/move was not being handled properly, and didn't work as a
result.

* Fixed inversion of flag checking logic.

* Added tests for interaction events and cursors.

* Removed now unused variables

Variables were private and readonly, so removal should not be a problem.

* Fix #3662

Needed better tracking of if events should have default prevented.