What was the case that centered around the issue of whether homeless persons could be banned from a library?

There have been so many that have touched upon homeless issues like body odor, staring, camping gear, stalking behavior, using the library premises for non-library purposes, but there has never been a legal case involving a library banning a patron because they have no permanent address.

Probably the most famous case is Kreimer v. Morristown Library: http://overlawyered.com/tag/richard-kreimer/

Note that the case was overturned and now it is common practice in the US that people who are offensive can be removed from the public library.