`unfinished-comments` - Detect the "Preview" tab

[fregante]

Description

1. Write a comment
2. Switch tab
   • the tab title is updated ✅

But:

1. Write a comment
2. Click the "Preview" tab
3. Switch tab
   • the tab title is not updated ❌

This should be as easy as detecting a selected, non-empty Preview tab

Example URLs

Here