Try typing non-ASCII characters in the VisualEditor edit summary field. For example, just type the Russian letter ж continuously. Towards the end it won't stop at 0, but at -1. Example screenshot from the Hebrew Wikipedia: http://j.mp/ZoQKX6 .
This should be handled in a cleaner way. Either disallow typing anything that would go beyond zero, or allow all text to go beyond zero, as in Twitter or MoodBar.