The multilanguage edition

Added

• I18n support. The extension now has additional files for language-specific strings, and now uses the i18n API to access localizations.
• Bulgarian language support.

Thanks to @StoyanDimitrov for providing these changes!

The "multiwindow" edition

Added

• New option to check duplicate tabs across all windows, instead of only the current one.

Changed

• Extension source now uses the AMO UUID, instead of one that was used for development. This only affects users that self-compile the webextension for themselves (if you're building from source for testing, install a separate copy of Firefox for development).

Fixed

• about:-tabs are now de-duplicated.
• Options page now retains the proper visual toggle state of the "old tab" option, instead of always being true if not set or false if set.

The autojump edition

Added

• New option to keep the activated tab in its current position, mirroring the browser's behavior of jumping to an existing tab from the address bar. Thanks to @StoyanDimitrov for the contribution.

The "webdev" edition

Added

• New configuration page in about:addons, to be populated with various options in the future
• Option to keep tabs explicitly duplicated via the "Duplicate tab" option or by middle-clicking on the refresh button. This allows for situations where you do need multiple tabs pointing to the same page.
• storage permission: This is used for the previously mentioned configuration options.

Changed

• The tab duplication check routine now uses the modern filter function on the tab list.
• Added padding to logo vector so the dimensions are square to pass the latest AMO validation.

The "middle-clickers" edition

New tab replacements will only be made active if the old tab was active.
This should make it less of a hassle for middle-clickers that want to check a look at an existing tab later.

The "sweep the floor" edition

Instead of the old behavior of replacing the checked tab with the first known duplicate, we collect all matching tabs, figure out the best one to keep, move it to the checked tab's location, and close the rest.

This should avoid cases where multiple tabs attempt to update and pick a different tab to update to, fixing #1.

The "stop querying hundreds of tabs repeatedly" edition

Added the url parameter to only query and match tabs with the same hostname.

First commit.

Basic extension to clean up duplicate tabs.