TabScroller от Richard Antony Burton

** A fix has been pushed to v1.0.10 where it may not work at all after updating. Please update to v1.0.10.1 it should be fine again. Sorry about that! **

A simple addon that does one simple thing. It allows you to scroll through your tabs with the mouse wheel, while holding the right button down (and/or keyboard modifiers). It directly changes the tab as you scroll, rather than showing a popup of tabs to scroll through. After moving to Firefox 57 the old addon I used for this purpose stopped working. I could not find a replacement, without going for a big addon with full gesture support like Foxy Gestures, so I wrote this one. It has minimal options: wrap around at the ends of the tab list (default on), invert the direction of scrolling, scrolling rate-limit (default off), a selection of keyboard modifier keys and a few options for skipping tabs when scrolling through.

Limitations:
- This addon works on Windows from Firefox v57 (and maybe earlier) and Linux from Firefox v58. Previously it did not work on OSX (due to lack of button info on the scroll event), but as of v1.0.6 I have got OSX to work via a different mechanism.
- This addon operates from within your tab content i.e. the mouse must be over the page, not over the tab bar itself (there is no WebExtension API for this).
- This addon will not work on most non-webpage tabs of Firefox, such as the Firefox options page, addons page or the new tab page. Mozilla also blocks addons from operating on pages from the addons.mozilla.org site itself.
- You can't scroll away from a tab that's not finished loading.
- Some pages that capture key presses could potentially interfere with the keyboard modifiers option (1 report with a specific Google Docs spreadsheet).

Please let me know if you have any difficulties. Bugs can be reported on GitHub.

Permissions:
- The storage permission is required to save the settings mentioned above.
- The browserSettings permission is required, but only used to enable an option needed for Linux/OSX support.
- The tabs permission is optionally used to access the url of tabs, to allow use of the tab skip by url feature.
- The scroll handler needs access to all webpages in order to work from them. This results in a scary permission request on install saying the addon can "Access your data for all websites". This is a just stock warning meaning the addon acts on all pages - please be assured your data is not being accessed at all. If you are concerned please check the source code in the xpi or on GitHub.