Feature Request? - Add new windows to bottom of tree rather than root.

[newmeta-ben]

Is it possible to have new windows added to the bottom of the tree instead of at the top level? Apologies if this has been submitted before, I'm sure I saw this somewhere but can't find it anymore.

I commonly run a left + right configuration with 2 applications side by side. It would be nice as a configuration option or a command to force all new windows to join the left or right already existing branch.

This is achievable via keystrokes, but I'm not sure if this can be achieved in the on-window create callback?

Something like: [[on-window-detected]] run = ['join-with right']

So instead of: App A | App B | App C

It would add as:

App A | App B
        App C

I don't think this is doable with the current configuration, but it would be super nice to be able to essentially add to the bottom left or right leaf of the tree.