Totally not Panorama (Tab Groups with tab hiding) от Nikolay Yordanov

To use this extension, you must go to about:config and set extensions.webextensions.tabhide.enabled to true.

Enhancements, compared to Panorama View 0.6.15 by photodiode:
- Support for hiding tabs (Firefox 59+)
- On-demand screenshots (Firefox 59+)
- Support pinned tabs
- Ctrl+E opens/closes the panorama view (Ctrl+Shift+E for Mac)
- The keyboard shortcut is configurable for Firefox 60 users. You can only set shortcuts which are not otherwise used by the browser.
- Dragging a tab out of a group creates a new group with this tab in it
- Resize and move groups
- Create a new group by drawing in the empty space in the panorama view

Limitations (compared to Tab Groups by Quicksaver):
- Doesn't work in Private Browsing windows
- No "Undo closed group" button
- No automatic group management - you need to assign tabs to groups manually
- No context menu actions
- Groups may overlap, you need to select appropriate sizes manually