Here's a simple, but useful, and undocumented tip.
In the track editor you may find that you can't see all of your notes in Piano Roll view without scrolling up and down. For example, in this view of a Drum region:
You can't see the Hi Hat or Cymbal hit without scrolling up:
And then, of course, you can't see the Kick and Snare without scrolling back down.
However a feature you may not have found is that you can stretch the editor pane by grabbing anywhere in the dark grey area and dragging up:
Thus transforming the small pane into a large one which displays much more of the editing area:
And as a bonus Quickie, the same thing works when you're editing an audio region, allowing you to see more detail in the waveform... from this: