Row Header and Cell Retrieval in the WPF Toolkit DataGrid Using the MVVM Pattern

using System.Windows;
using System.Collections.Generic;
using System.Windows.Input;
using System.Windows.Data;
using System.ComponentModel;
using RowHeaderGrid.Models;
using RowHeaderGrid.Commands;
using RowHeaderGrid.Views;
using RowHeaderGrid.Utils;
using RowHeaderGrid.DataAccess;
using System.Collections.ObjectModel;
using Microsoft.Windows.Controls;

namespace RowHeaderGrid.ViewModels
{
    public class MainViewModel : ViewModelBase
    {
        private DelegateCommand exitCommand;
        public DelegateCommand<DataGridItem> CellClickCommand { get; private set; }

        IList<Item> _items;
        public IList<Item> Items
        {
            get { return _items; }
            set
            {
                _items = value;
                base.OnPropertyChanged("Items");
            }
        }

        #region Constructor

        public MainViewModel()
        {
            _items = DataAccess.DataAccess.LoadItems();
            CellClickCommand = new DelegateCommand<DataGridItem>(CellClickSelection, CanCellClickSelection);
        }

        #endregion

        public ICommand ExitCommand
        {
            get
            {
                if (exitCommand == null)
                {
                    exitCommand = new DelegateCommand(Exit);
                }
                return exitCommand;
            }
        }

        private void Exit()
        {
            Application.Current.Shutdown();
        }

        private void CellClickSelection(DataGridItem item)
        {
            MessageBox.Show("Cell's column is " + item.Gridcell.Column.Header.ToString() +
                            " it's ID is " + ((RowHeaderGrid.Models.Item)(item.Gridrow.Item)).ID);
        }

        private bool CanCellClickSelection(DataGridItem cell)
        {
            return true;
        }
    }
}