Tab Teleporter от Peter Simonyi

Dragging tabs around can be a drag. Move tabs with the context menu instead.

• Mark a tab as a target, then move tabs beside it
• Move to the left/right end of the tab strip
• Move to an existing window or create a new one

Permissions and privacy:
Access browser tabs is required for obvious reasons.
Access recently closed tabs lets tabs you mark as teleport targets remain marked after undo-close-tab and after restarting Firefox if you have enabled the preference "When Firefox starts: Show your windows and tabs from last time".
Access your data for all websites is a technical workaround for limitations in the WebExtensions API. There is no way to visually mark individual tabs, so this extension marks tabs by updating the page <title> in order to change the tab title. No other changes are made to websites, and it does not read information from any websites.

Note: The workaround for marking tabs described above means that certain tabs will not appear to be marked. This includes special Firefox pages such as Preferences and the Add-ons Manager, and certain sensitive Mozilla domains such as addons.mozilla.org.

About your rights:
This extension is Free Software, made available under the terms of the Mozilla Public License, version 2.0. You can download the source code from the repository on GitHub.