nsMsgFilterDataSource has its own nsISupports implementation instead of inheriting from nsMsgRDFDataSource. This means that opening the filter list dialog generates the following assertion: ###!!! ASSERTION: AddObserver: trying weak object that doesn't support nsIWeakReference: 'weakRefFactory', file c:/mozilla/xpcom/ds/nsObserverList.cpp, line 79
Created attachment 156628 [details] [diff] [review] No need to redefine, just inherit
Fix checked in.