I wrote a powerful database GUI as an applet, to pick up an update all the user had to do was save their work and hit the refresh button. I used Symantec Visual Cafe.
And none of the above are necessary elements of a reinvention.
In fact, it's the current web one-page-app mess that is a re-invention of the notion of the Java applet warts and all: it's slow, has crappy GUI support, and it's a mess to develop in (like Swing was over-engineered crap).
We could use an actual sandboxed, "runs code from internet resources" platform, that contains the whole stack rethought and simplified.
That would be exactly like the Java applet, except with a much better API (and touchscreen laptops would finally make sense).
As usually with interesting ideas someone beat you to it:
http://www.appcelerator.com/blog/2014/01/browser-based-emula...