Should be possible on Ubuntu. I have most of this set on my KDE setup, but harder to configure than back when i used FVWM. You can at least set sloppy focus.

Should be possible on Ubuntu. I have most of this set on my KDE setup, but harder to configure than back when i used FVWM. You can at least set sloppy focus. I haven't bothered to look if you can still open behind/lower on open.