Keni
Please please always post steps to reproduce, like below, please never make assumptions, some of us always going to misunderstand or don't have the right knowledge :) It might seem a waste of time but I can assure you it isn't if you want everybody to understand....
STEPS 1) Open project
2) Go to MIDI track. View -> Piano Roll View
Now how are you zooming in/out? Scrollbars.
Then what do you do? (Baby step by step please,)
What is EXPECTED behaviour , What is ACTUAL behaviour...
BTW it isn't a bug if the facility isn't available, it is a feature request.
Thanks.. :) :) :)