Prevent scripts from bringing down the app.

If someone writes a script and runs it in the app and the script has
errors, the author should be informed without bringing down the entire
application.
Prevent scripts from bringing down the app

this change too
Push the find results enumerable higher in the app.

By pushing the enumerable all the way to the MultiBoxControl, the
MultiBoxControl can choose to do the job of enumerating on a background
thread or in some way that increases the performance of the enumeration.
It doesn't yet, but now it can.