Bug Fix: Fixed broken FilterBar in ListView

@halatmit @jisqyv @afmckinney Fixed broken FilterBar in Listview - related to issue 182:
https://github.com/mit-cml/appinventor-sources/issues/182
I don't think this is correct.  When I try Taifun's example, I get b2 as the selection (which is correct) but I get 2 as the selection index (rather than 4).  Can you take a look?
@kkashi01