I trying to make a clean-room prototype of new Package system (yeah yeah..:) The idea is following: the package(s) is in control! I.e. each change to package contents should pass validity checks before getting applied. This would allow us to enforce some policy, which could help to maintain a code in system in good shape. For instance, the most wanted feature, as to me, is to ask package if it: - allows extending other packages by extension methods - allows extensions to be added to package own classes the problem with current kernel, that it never asks anyone if it allowed to do something or not.. instead, the code applies change, and only then using SystemChangeNotifier to broadcast the event of change to any interesting parties.. Such approach hinders any attempts to build a secure system, because once change is made, it could be too late to revert it and its very easy to bypass any system facilities which normally could prevent the user from doing wrong things (like removing Delay class or one of its critical methods ;). And there is a SystemEditor, which unfortunately, not ready for use with Traits :( but afaik, it don't providing any means to validate the changes before applying. Or does? Maybe its worth to create another notification which can notify the interesting parties before the change will be applied? What you think? -- Best regards, Igor Stasenko AKA sig.