Instead they all insist on having just one window with a 10-kilometer long list of rooms/chats/channels on the left that you have to switch between in a single window.
This becomes especially frustrating when you have several active chats going on at the same time, or when you want to retain some info on the screen while answering in a separate chat/channel.
I constantly find myself switching between the Calendar view / channel view when planning a meeting, or between channels when referencing a PDF shared in the "Files" section of a different channel. Super annoying.
The editor of the current file is the current opened room, and tabs to switch between rooms. The explorer shows rooms as files and spaces as folders that can be expanded/collapsed. Also support for keyboard shortcuts like CMD+P to quickly open a room.
You still have to use the same window to switch between them.
These are not tabs.