Lack of extension popup UI

Nothing happens when clicking on the extension icon because there's only an options page.

This may explain the following review:
https://chromewebstore.google.com/reviews/57c0f272-55f0-41bd-b934-0af49f499596 `The extension just appears grey and it doesn't work anymore`

Likely would be value in having a popup UI (also allows adding per tab controls)