I inadvertently keep activating a little track list menu on left mouse click in the PRV. It looks useful but I don't know how I keep activating it and have trouble deactivating it. It's a list of the tracks I have picked to be seen in the PRV Track Pane. I couldn't find any information on it in the reference guide. Any guidance would be appreciated.

Do you mean this:
 

 
This is toggled in View > Show/Hide Track Pane in the prv.
 
As far as I know, you cannot enable this with a single mouse click

You can drag it open by the pane divider even when it's fully closed, but if it's popping open with a single click, I would suspect an issue with the persistence of the pane size in that particular project or version of SONAR. Is this happening in the current release of SONAR 2015?

I know you can Hide/Unhide it by pressing "H", but it shouldn't be doing that on a mouse click. I can't seem to make that happen myself.

I vaguely recall that an earlier version of SONAR would give you a mini track list when clicking with a certain tool or editing mode. Not sure how far back that was.

It is not the PRV Track Pane that pulls out from the right. It is this menu that appears when I left click on an open area of the PRV. Which normally would envoke using the Smart Tool. The items on the list are what I have visible in the Track Pane. I am using 2015 Platinum. Thanks for the help all.

Yes, that's what I thought you were talking about. The pop-up is just asking you which track you want to edit.

Yeah, I know. But I can't figure out what I did to make this menu appear. Or go away. Thanks

For example, if you picked four tracks (guitar, bass, piano, drums) to show in the PRV and let's you're editing the guitar track, then if you open the Pick Tracks menu and remove the guitar track and go back to the PRV, the view needs to know which of the three remaining tracks you want to edit. Makes sense?

Ah. I must have no track selected when this menu appears. That makes sense. So rather being frustrated at seeing this menu, just select one of the tracks from it. My PC is off but I will try this tomorrow. Thanks for the help.