public override int SetSite(Microsoft.VisualStudio.OLE.Interop.IServiceProvider site)
        {
            base.SetSite(site);

            listener = new ProjectDocumentsListenerForMainFileUpdates((ServiceProvider)this.Site, this);
            listener.Init();

            return VSConstants.S_OK;
        }
        public override int Close()
        {
            if (listener != null)
            {
                listener.Dispose();
                listener = null;
            }

            return base.Close();
        }