EsotericSoftware/spine-runtimes — pull request #267 by NimaiMalle (2014-08-05 12:41:29+00:00)
Title: Listener class improvements

Changed the add function for Listeners to not add the same listener function more than once.
Changed the remove function for Listeners to not delete the last listener in the list if the requested listener isn't present in the list.
Added a "has" function to test whether or not a listener function already exists in the list of listeners.