It's just a stupid and simple thing. But I think it'd make MusicBee easier to handle.
Currently, you can choose in preferences if you want to play or to queue a song when you double click. It means that if you chooses 'playing' you must use the contextual menu to queue a song. You can use a hotkey, but you have to go from mouse to keyboard and go back again for each song.
Why not using a kind of 'fake hotkey'? Something like:
If playing is selected:
> Double click plays a song
> Alt + Double click queues a song
If queueing is selected:
> Double click queues a song
> Alt + Double click plays a song
So you never need to go to the contextual menu