Focus on hover of a non-focused popup

In some ways the opposite of #64 - keep single-click actions, but make it possible to raise the TF popup even if it is partially obscured. E.g., hover for >1s (user-selectable threshold) activates the popup.

(Alternative: raise a modal on hover >thld, and have the modal swallow the click and dismiss itself.)

No files or tests are named. Start by locating the popup's hover and single-click handling, then check how partially obscured popups are raised. Done means preserving single-click actions while implementing a user-selectable hover threshold, or resolving the modal alternative, with coverage for dismissal and obscured popups.

Written by the indexing model from the issue text.