I’m a loooong time Cubase user, actually from Pro-24 on Atari 
I can’t remember on which Cubase version, but about 12 years ago there was a Tool Toggle function that was very handy while editing audio or MIDI: any tools selected (mute, rubber, ecc.), you could have a key toggling between that tool and the arrow tool…
I know, it sounds nothing special if you haven’t tried, but I swear, it was making my editing workflow waaaaaay faster!
Than with some new version, a long time ago anyway, it just disappeared.
Does anybody know if there is a way to do it today?
Thank you!!!