It would be awesome if we could bookmark an entire tab group with drag and drop to the bookmark side bar or bookmark toolbar. The bookmarks could be saved into a folder with the tab name as a folder name, or if no name has been set FF could prompt for one. Already when dragging a tab group to the bookmarks side bar FF indicates the position of dragging in the bookmarks list with a color stripe but does not add the bookmarks when releasing the mouse button.
Also, a right click option for bookmarking the tabs when right clicking on the tab group name / color square wouldn't hurt. That could bring about a popup to choose the subfolder where to save the group in a folder with the group name with a text field to edit or enter the fodler name.
I already submitted this once, but it doesn't appear in the feed, so re-submitting now.