I installed 1.6.3, configured the Adafruit proxy and all was well. No module to test yet, but I was able to install support for the ESP8266 and compile programs without problems. Next day, I started getting "compile error" when I tried to compile anything for that board, even an empty sketch. No other messages. I tried various combinations of removing and reinstalling the ESP8266 support, and the IDE itself. Installed originally as a Zip, I tried the windows installer too. Now all I get is the splash screen, and the message "installing packages", and then it dies. No apparent remnants that I can find with Task Manager. I restored my Win7 to an earlier version which did nothing to help. I'm getting very frustrated and quickly losing hope. Any ideas?
Thought I would pass this on to anyone who is having a similar problem. There was a corrupted file in …/uers/username/AppData/Roaming/Arduino15 that was causing the problem. Deleting the directory fixed it. But using the Adafruit board manager proxy broke the IDE again, so I’d stay clear of that feature until it stabilizes a bit.