I can't find the thread now, but we discussed this very good idea earlier. I'll just place another ++1 here, you never know... I proposed to make each click on a plus open up a cc lane showing the next used controller as long as there is any. So basically all you'd need to do was spawn new lanes until the lane doubles, telling you that all used cc's are now shown in a lane. For the pop up list, I'd find it useful if all used cc's are gathered on top of the list, so you wouldn't have to scroll-search for them in the list. Used cc's are shown in italic and cc's already shown in a lane in bold. Btw, this would also be a huge help in the track automation list that can grow huge for certain plugins. Here's the mockup I made back then to illustrate the feature: