public MainViewModel(IEditingContext editingContext, IDesignCommandHandler designCommandHandler)
        {
            EditingContext       = editingContext;
            DesignCommandHandler = designCommandHandler;

            // Since we're Main, we have to instance the document into the editing context.
            EditingContext.Document    = new Document();
            ChangeSelectedItemsCommand = new DelegateCommand(ChangeSelectedItems);
        }
        public MainViewModel(IEditingContext editingContext, IDesignCommandHandler designCommandHandler)
        {
            EditingContext = editingContext;
            DesignCommandHandler = designCommandHandler;

            // Since we're Main, we have to instance the document into the editing context.
            EditingContext.Document = new Document();            
            ChangeSelectedItemsCommand = new DelegateCommand(ChangeSelectedItems);
        }