Question: I'm using a ‘session group’, to keep multiple OS-level, window-managed terminal windows open to different `tmux` ‘windows’ (so they share a default working-directory, `tmux` settings, etceteras.) Those Terminal windows are different sizes.

Normally, from a larger Terminal, I can do the following to start a new command:

```
:new-window vim

```

![](https://i.stack.imgur.com/mntDx.png)

However, if I *ever* switch to a different pane with that new, larger Terminal window, I am foreverafter stuck with this, when I switch back:

![](https://i.stack.imgur.com/mt0Ei.png)

I have to kill the entire session, create an entirely new session, and link it to the session-group again, using `tmux new-session -t <blah>`, to restore the full terminal-width.

Is there any other way to restore / change / set the ‘available width’ of a session (or window, idk)?

Answer: 
Perhaps enabling the aggressive-resize option will help:

```
set-window-option -g aggressive-resize

```

A good overview of tmux options is given [here](https://mutelight.org/practical-tmux).
Starting with tmux 3.1, the default option for `window-size` is `latest`. So all you need to do is upgrade.