Add touchpad gestures
Touchpad gestures (e.g two-finger swipes) are a crucial part of being productive on a laptop, and as such, Kalendar should implement some of those.
In my opinion, the most important one would certainly be swipes for moving through the calendar view. Lateral gestures would go back/forward a time unit (day, week, month), depending on the view, and if on the month view, up/down could go back/forward a year, respectively.