What else do you think is missing?

Update:

Thanks for updating your review with the suggestions.

1) Rebinding the popup key isn't possible in Firefox yet unfortunately. It'll be possible in future Firefox versions but I don't know exactly when. All we can do now is watch for the progress on this: https://bugzilla.mozilla.org/show_bug.cgi?id=1303384

2) Pressing enter from the search input should enter the first item in the tab list, but having a visual indicator to make this more obvious is a great suggestion.

3) Another good idea. Will definitely add this.

W.r.t to history and bookmarks, I'd love to add them. My main concern is presenting them in a way that doesn't clutter up the search results too much. Here's an open issue on GitHub regarding bookmarks: https://github.com/reblws/tab-search/issues/20 . If you have any more suggestions don't hesitate to contact me by email or comment in the issue tracker! https://github.com/reblws/tab-search/issues