JakeWharton/ActionBarSherlock — pull request #81 by zachlipton (2011-10-19 22:39:11+00:00)
Title: Fix NPE when calling ActionBarImpl.getNavigationItemCount() when tab navigation is enabled and no tab is actually selected. Return -1 in this case, which is what the Honeycomb implementation does.

Returning -1 is undocumented behavior, but empirical observation reveals this to be a part of Google's implementation.