fixed call to createFilterFn in onTypeAhead
item close button did not appear under Ext 4.2.0
previous selection lost upon making new selection

The set of filtered records (valueStore) were REPLACED by selected
records in the page currently loaded in the combo box store (store).
Consequently, the user's previous selection was lost when the user made
a new selection from a disjoint page loaded into the combo box store.
fix oversized styling of combo box under Ext 4.2.0

This solution was contributed by user "WebProgrammer" on Sencha Forums:
http://www.sencha.com/forum/showthread.php?134751&p=952915
error underlining did not appear under Ext 4.2.0