Ah, works perfectly, thanks. Maybe it's still a bug when used with the desktop rules, though.

Delete the rule. Then go to "Assign applications", assign MusicBee to all desktops and restart it.

I have a window rule set up to copy MusicBee (by matched executable) to all desktop windows. That works fine, but now, every time the MusicBee window's title changes (for example on song change), focus is stolen from whatever application is in the forefront (so if I'm doing programming work, I can no longer type).

If I disable the rule, focus is never stolen. Maybe there's a simple setting I'm missing here?