Someone pointed out to me that the change in #1433 doesn't work when plots are embedded within QDockAreas (the cursor never changes). This is probably related to the Qt bug discussed here.
To reproduce the issue, under MPL 1.2.0: https://gist.github.com/4208745
This PR sets the cursor at a different level in the widget hierarchy, and seems to sidestep the problem.
Note that I haven't checked whether this change breaks the original problem addressed by #1404
Workaround Qt cursor bug when placing plots in Qt Dock area
Cheers @ChrisBeaumont. I can confirm this fixes the issue. Merging.
This is a pretty nice fix and it's a ridiculously tiny change. @mdboom Can I cherry-plonk this into v1.2.x?
Yes: I think this makes sense to put on 1.2.x.