Having an application on the correct screen

[David Edmundson]

If the app is positioning themselves, they'd need to know the global
mouse position which we don't export.
That would be a weird thing to export and trying to re-create X rather
than do things properly.

layer shell (https://github.com/swaywm/wlr-protocols/blob/master/unstable/wlr-layer-shell-unstable-v1.xml)
positions things semantically rather than explicitly. That has the
concept of not setting an output, so the compositor can choose which
to use, and that has access the cursor.

I think long term that's where we want to go.

That's quite a big change and implementing the client side properly
means doing things in a different way to how we've currently done
things.

David