Tabs on the left and right edges of the windows work much better than top or bottom tabs, because text is wider than it is tall, so you can fit a lot more tabs, and actually read their labels.

Users should be able to decide which edge and position each tab is attached to, and move them around and group them as desired.

These are the tabbed windows I developed for the multi-window version of UniPress Emacs 2.20 in 1988:

https://en.wikipedia.org/wiki/Tab_(interface)#/media/File:Hy...

Users could move the tabs to any edge of the windows in the NeWS PSIBER Space Deck, in 1989:

https://medium.com/@donhopkins/the-shape-of-psiber-space-oct...

Figure 3 shows the class dictionary of Object, and the instance dictionary of the NeWS root menu:

https://cdn-images-1.medium.com/max/800/0*y5wrMJUyP69L4_9r.g...

Figure 7 shows some digit editors, step editors, shift editors, a boolean editor, and a canvas editor:

https://cdn-images-1.medium.com/max/800/0*5srS0w6nxQwTSCmq.g...

The tabbed window manager for The NeWS Toolkit let users drag tabs to any position along any side of the window:

https://www.youtube.com/watch?v=tMcmQk-q0k4

Previous HN postings about tabbed windows:

Side tabs are great, because text is wider than it is tall, so you can fit a lot more of them on the screen, to manage more windows. (2014):

https://news.ycombinator.com/item?id=8042726

"As if all that wasn’t enough, there’s also the matter of tabs. Tabs are a couple of decades old now, and, like much of the rest of the desktop and web environment, they were initially thought up in an age where the predominant computer displays were close to square with a 4:3 aspect ratio." Tabs are at least three decades old now, and they weren't originally restricted to just one edge of the window (2018):

https://news.ycombinator.com/item?id=16875730