How to support ListBox SelectedItems binding with MVVM in a navigable application

Question

I am making a WPF application that is navigable via custom \"Next\" and \"Back\" buttons and commands (i.e. not using a NavigationWindow). On one screen, I have

Answer 1

This was pretty easy to do with a Command and the Interactivities EventTrigger. ItemsCount is just a bound property to use on your XAML, should you want to display the updated count.

XAML:

ViewModel:

    private int _itemsCount;
    private RelayCommand _selectionChangedCommand;

    public ICommand SelectionChangedCommand
    {
       get {
                return _selectionChangedCommand ?? (_selectionChangedCommand = 
             new RelayCommand((itemsCount) => { ItemsCount = itemsCount; }));
           }
    }

        public int ItemsCount
        {
            get { return _itemsCount; }
            set { 
              _itemsCount = value;
              OnPropertyChanged("ItemsCount");
             }
        }