Just posting to give a Public Service Announcement about the “active” tab behavior in Application Studio.
I have been working on a customization with similar event flows and when I go to test them, funky stuff keeps happening. I have had a bunch of the events open in tabs and was expecting that when I click on an Event Next to open that event, that when I close the opened event, the system would go back to the last “active” tab that I opened the Next Event from. Well, it does not. It goes to the furthest tab on the right. 
I have been struggling for 2-3 days until I just realized this. So if this saves one person the same frustration, I will be happy.