@SallyMeander: In the case of a casting problem, you'll have to
walk up and down the code to see where that object is used both
before and after the line of code you changed. I'm not familiar
with that project. It's a bit old and from a specific
presentation, so there might not be anybody here who knows it
either.  You might have better luck on stackoverflow.com, which
is a development Q&A site.