GUACAMOLE-231: Merge mouse update fix.
GUACAMOLE-231: Merge mouse update fix.

apache/guacamole-server,glyptodon/guacamole-server,glyptodon/guacamole-server,apache/guacamole-server,mike-jumper/incubator-guacamole-server,mike-jumper/incubator-guacamole-server,mike-jumper/incubator-guacamole-server,glyptodon/guacamole-server,mike-jumper/incubator-guacamole-server,apache/guacamole-server