This does not appear to be a mootools is, rather a browser issue. If I attach the 'contextmenu' event to a container. As expected all children bubble up the event. This works in Safari 3, FF2, FF3 (PC), IE7, Chrome. However, in FF3 on OS X it doesn't seem to be working properly for me.
For troubleshooting purposes I even disabled all plugins and restarted the browser. Still the same effect. FF2 on Mac works fine. Has anyone else run into this?
