Your comments
Yes, subfolders would be great !
I have exactly the same problem with Win10, latest Firefox and the latest Speed Dial 2.
Firefox keeps opening a new tab, closes it, opens it again with a new page, closes it on and on.
Super annoying. When I disable Speed Dial, everything goes normal again with only one tab.....
Customer support service by UserEcho
But not if it takes 4 more years to implement :(