I've been playing with nsISecurityCheckedComponent quite a bit lately and have been wrestling with getting it to work on a js implemented component. I was even trying to use aggregation to have an 'inner' class do the implementation (need to have nsISCC implemented on lots of classes).

I just discovered an issue that I hadn't expected. When implementing nsISCC and nsIClassInfo the call to getClassDescription is actually a check for a property and causes the canGetProperty() method to be called asking about classDescription. Good times. I hadn't even thought to add those pieces to the list of approved properties and methods. Now I know.