I've been thinking about dipping my toes into GCW development, because it looks like it might be fun. I've done simple programming in several languages, so this certainly wouldn't be my first project ever, but I don't know how to specifically write and package a GCW app. It would need, at minimum, a window with the words "Hello World" on it. (I'm sure you can write command-line programs for it, but that doesn't seem like a good idea.)
So, how do I get started?