Well, I pulled the plug on the network - and I had Intelligent Services checked and I got the Editor Pane, and I could not induce it to revert to the 2007 dialogue! I checked Intelligent Services - same deal.
I'm going to do a no-network test with everything in Settings checked
Oh, I discovered this morning that setting of Windows Default Programs is even worse in 1803 than it was in 1709 --- just like they did the previous bazillion times they've tampered with it. And they nuked the old one in Control Panel.
BR