Pin Unpin Tab is a Firefox WebExtension to pin or unpin a tab by

• a long left mouse click anywhere on the webpage (an arguably more efficient alternative to the no longer possible double-click on tab)
  • This option can be enabled or disabled on the add-on's preferences page.
  • The minimum duration to hold down the click can be set.
  • This approach will not work on AMO webpages and the Firefox pages (eg., about:addons)
• a click on the pin icon on browser toolbar
• a keyboard shortcut Alt-P (Ctrl-Shift-P on macOS), which Firefox allows to customize. See the guide here.

Note that double-click on a tab (active or not) to pin/unpin is not going to be possible due to the limitations of the WebExtensions technology. Only Mozilla can fix it, not me. Look here and here for more details.

Credits

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