I cannot restore the Expand/Collapse button in my track panes.  They were showing up, but I believe I hid or made them go away by accidentally pressing a key or key combination on my keyboard.  Does anyone know how to restore this button?  I thought it should be easy to find information on this in SONAR help or the forum, but after 30 minutes of searching, I could not find any.   
 
I am running SONAR X2 Producer.

Do you mean the double-arrow maximize/minimize button?

Hi, and welcome to this forum. Maybe you have Auto Track Zoom enabled in track view? Alt+Z is the shortcut for that. Hope it helps.
All the best.

Yes it is the double-arrow Maximize/Minimize button.
 
No, sorry, the Alt-Z did not work.

Deselect this option

Thanks scook.  That worked.
 
Zargg71 - the Alt-Z did not work, but once I deselected "Auto Track Zoom" from the menu option, restoring the double arrow button, I tried Alt-Z again.  It worked to select ATZ, but ALT-Z does not work like a toggle.  IOW, it only works one way - to select ATZ.  Don't know if that's by design or it's a bug.