Good to know that Session detach was added 2+ years ago.
Are tmux keybindings first class citizen in Zellij? and what would you say sets Zellij apart from tmux based on your experience?
Yes they are. They work out of the box as I mentioned. This is what originally helped me move from screen to tmux, so it was important to me to provide the same experience.
As for comparisons to tmux: I shy away from those. Just like I shy away from comparing chocolate cake to lemon cake. Both are awesome. Use what you like and decide for yourself.
