TabSlicer от Shane Uriarte

This is a tab based extention for Firefox optimized for Windows. Through adjustable hotkeys, you can duplicate a tab, select tab(s) from one browser source to be split from all other tabs in that browser source. An immediate reversion feature works through best effort means to return split tabs to the same browser.
Queue of tabs can be viewed in the extension or sidebar popup.

Helper: Use of this extension is optimized/improved by a Windows Host helper program to enable operating system specific window snapping. This is COMPLETELY OPTIONAL and can be found here: https://github.com/SaxbyVS/TabSlicer_helper/releases/tag/2.0_helper