[WIP] Focus share link when pop-up opens

Fixes #1673 by waiting for the dropdown to open and then selecting and focusing input.

- [ ] Needs tests.
Okay. I decided to hell with it. It's only a couple lines so let's re-implement it. I would rather receive the event and have to duplicate that tiny document click handler than have to sniff the class. Rebased to master, forced my changes on top, and added tests.