I had to play with the new UI a while before figuring it out. No delete panel but when you go back in time to the left and click a different link, everything that had been to the right of the "clicked panel" disappears. So, you have to sometimes use your browser's "open in new tab" functionality to remember a context for later use - this goes against the one page web app concept, but makes it workable for me. BTW, interesting that the Node server code is written in CoffeeScript.