FigureCanvasMac.flush_events() raises NotImplementedError

[Original report at SourceForge, opened Thu Mar 10 10:39:14 2011](https://sourceforge.net/tracker/?func=detail&aid=3205539&group_id=80706&atid=560720)

FigureCanvasMac seems like it should be a "backend with GUI", but it doesn't implement flush_events(). Seems like it should `pass`, if nothing else.
### SourceForge History
- On Fri Mar 25 18:54:33 2011, by pivanov314: assigned_to: 100
