In the extras directory you're going to find this neat little utility that allows you not only to edit boo scripts with a nice syntax highlighting but also to run them (F5) and/or see their expanded form (CTRL+E).
booxw can be found in binary form here.
If you want to build it yourself follow these simple steps:
Here's a screenshot of boox in action to whet your appetite:
I've started a similar project using Gtk# but It's in a very early stage. If you know or want to learn how to write Gtk# applications this could be a good chance.