I made a video of the one remaining issue with making this work well:
https://www.youtube.com/watch?v=MvBjtqNap0g&feature=youtu.be

Thanks to Nischay's efforts, we have a mostly working dialog box for adding properties to links --- the user story works very well. This will be available in a public git repo as soon as Nischay pushes it. It has one bug and one missing feature. We hope to get guidance from the VE dev team on these two issues:

We are hoping to find (or help create) an externally defined interface on VE, so that we can write an extension that provides customized keyboard functionality. The extension might use non-jequery.uls components. (Our company is using VE in our commercial products, and while we intend to make the keyboard extensions fully FOSS, we might have non-mainstream requirements that are hard to meet with only jequery.uls components.)