Plot options histogram infinite loops after scrolling away

[stscijirahubjdat]

Issue JDAT-4723 was created on JIRA by Richard O'Steen:

Currently the plot options histogram can get into an infinite loop state that break the notebook, oddly by scrolling down in the notebook away from the Jdaviz app and then back up so that the histogram is in view. At first I thought that this was triggered by unit conversion but it's easier to trigger than that. I think this is a bad enough bug that it should block the 4.0 release.