public class WeakEventHandler
    {
        object strongTargetReference;
        WeakReference weakTargetReference;
        MethodInfo method;
        public WeakEventHandler (Action action)
        {
            strongTargetReference = action.Target;
            method = action.Method;
        }

        public void Invoke ()
        {
            if (strongTargetReference != null)
                method.Invoke (strongTargetReference, null);
        }

        public void MakeWeak ()
        {
            weakTargetReference = new WeakReference (strongTargetReference);
            strongTargetReference = null;
        }
    }