[Vala] Program doesn't quit

[Steven Oliver <oliver steven gmail com>]

For the past year or so off and on I've been working on a pet project.
Between the time spent rewriting various parts of it over and over, and
trying to learn Vala/GTK, it's taking me a lot longer than I hoped it would.

Anyway, here is my project on Github:
https://github.com/steveno/balistica

While I'm sure there are plenty of improvements that can be made (patches
welcome!) I have one problem that's been driving me crazy for a while now
and I'm desperate for help now to solve it. I assume the problem has to be
in src/BalisticaApplication.vala or src/MainWindow.vala.

If anyone is willing to offer any suggestions I'd greatly appreciate it!

Steven N. Oliver