This seems like a very useful and non-controversial fix -- and given that 1.2.0rc1 didn't get out yesterday, maybe it should go in? @efiring, @pelson, and other mac users -- do you agree? Any downside to this?

Fixing this will be great, and putting in the missing dynamic_update method makes sense. It looks like the simplest and safest way to fix a major shortcoming of the macosx backend.
Longer term, I note that dynamic_update is commented in the other backends (but not in backend_bases) as a "legacy method", however, and the only place it is used is in backend_bases drag_pan(). At some point, if not now, it presumably makes sense to replace it there with canvas.draw_idle, and consistently mark dynamic_update as deprecated. I haven't checked carefully, but I suspect it can be completely factored out into backend_bases.

I wonder if this would bring us a step closer to fixing issue #531? I have no pretense that it would be solved for v1.2.x, but I was just curious if this is a step in the right direction for it?

@WeatherGod, I don't think this is related to #531.

@mdboom, I think this should go in before rc2. It is a straightforward fix for a major shortcoming.

Merging into 1.2.x