Record at 50% speed

I would like to record a MIDI part slower, let’s say at 50% of my current tempo. I can change the BPM but I have to change it back and it is really not idea because it is freaking me out. I understand the Shuttle speed control might be designed for that purpose, but I don’t understand how to use it:

  • it is working as I expect when I mouse down to 50% but I can’t play my keyboard then (my mouse is down)
  • shift + right arrow plays at 100% minimum, even if I change the Varispeed %.