Apple Logic Pro X - Manual (Page 346)

Chapter 12 Edit MIDI regions in the Piano Roll Editor 346
Open the Piano Roll Editor as a separate window
Do one of the following:
m Choose Window > Open Piano Roll, or use the Open Piano Roll key command (Command-6).
m Drag the Piano Roll Editor by its title out of the main window.
Vertically resize the Piano Roll Editor
m Place the pointer in the bar at the top of the editor, then drag upward.
Drag downward to make the editor smaller again.
Hide or show the local Piano Roll Editor inspector
m To hide the Piano Roll Editor inspector: Choose Hide Local Inspector from the Piano Roll Editor
View menu.
m To show the Piano Roll Editor inspector: Choose Show Local inspector from the Piano Roll Editor
View menu.
Close the Piano Roll Editor
m Click the Editors button .