What would come in really handy would be a set of buttons for activating midi input - like the mute/solo switches - in a quick way. Or have a popup/dialog for this.
At the moment you can

• either: click the settings-icon of your instrument and than navigate through MIDI -> input -> and then check your device, which is too many steps/clicks when you want to add music to multiple tracks and have to change midi input more often
• or: open the instrument -> MIDI tab -> green light for "enable midi input". looks handy, but: it forgets the device, you checked, so when reactivated you have to select the input device again

Probably someone wrote all that before and I just didn't find it, so feel free to delete, when duplicate.

And hey: great software by the way!