Expanding multiple track panes at once? I forget.

There are two states. Auto zoom and not auto zoom. Shift+z to toggle these states.

With auto zoom you can adjust height of ask non in focus tracks at once by adjusting any one.

With auto zoom off, select all, ctrl or shift+ click resize to adjust all. You can also double click to toggle between full screen and not full screen on any track in this state.

In Track View there are two states for zooming and sizing tracks.
a. Original (opposite of auto zoom) shift+z to toggle states
 1. double clicking any track header in the gray area magnifies it to the full height of the track view pane.
 2. selecting multiple tracks, hold shift, and resize any one (while still holding shift) let go of mouse, let go of shift and the selected will resize to the same height.
b. Auto Zoom
 1. track in focus is sized independently of tracks not in focus
 2. all tracks not in focus are the same height all the time, so resizing any one of them resizes all of them.
 3. In this state, the track in focus is usually obvious because it will generally be larger than all the other tracks.