Context Plus от Michael Westbom

Now that tabs can have distinct contexts, it would be nice to move a tab into a different context. This allows that to happen. Right click on a tab, and under 'Move to context', and you may select the container under which you'd like to replicate the current tab.

If you hold ctrl while selecting a context, the tab will be copied, but the original will not be deleted (Only available in Firefox 54+).

Note that this addon does not replicate the browser history of the tab to be replaced. It essentially deletes the old tab and creates a new one with the same URL, in the same place in the tab list, with the new context.

Also note that you must have privacy.userContext.enabled enabled in about:config in order for this to do you any good.

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