Simplify show/hide of groupselector

The show function was not hiding other selectors correctly
when clicking between multiple selectors as this.shown
would get out of sync. Replaced that with a class.
Also saw no need why these methods need to return false.
Also corrected a comment.

Change-Id: I90cbccd5ed29ee7250bdb4e488e533043ca8eb95
Merge "Simplify show/hide of groupselector"