Navigating the different modules through a TreeView and ToolBar with Prism

using System;
using System.Collections.Specialized;
using System.Linq;
using System.Windows;
using System.Windows.Controls;
using Microsoft.Practices.Prism.Regions;
using System.ComponentModel.Composition;

namespace NavInfrastructure.Prism
{
    /// <summary>
    /// Adapter that creates a new <see cref="AllActiveRegion"/> and binds all
    /// the views to the adapted <see cref="ToolBarTray"/>. 
    /// </summary>
    public class ToolBarTrayRegionAdapter : RegionAdapterBase<ToolBarTray>
    {

        public ToolBarTrayRegionAdapter(IRegionBehaviorFactory regionBehaviorFactory)
            : base(regionBehaviorFactory)
        {
        }
        //// Recomendate documentation PRISM Appendix E: Extending Prism 
        protected override void Adapt(IRegion region, ToolBarTray regionTarget)
        {
            // Correctly reference
            if (region == null) throw new ArgumentNullException("region");
            if (regionTarget == null) throw new ArgumentNullException("regionTarget");

            // Reaction of the changes field ToolBars in ToolBarTray
            region.Views.CollectionChanged += (sender, e) =>
            {
                switch (e.Action)
                {
                    case NotifyCollectionChangedAction.Add:
                        foreach (FrameworkElement element in e.NewItems)
                        {
                            regionTarget.ToolBars.Add(element as ToolBar);
                        }
                        break;

                    case NotifyCollectionChangedAction.Remove:
                        foreach (UIElement elementLoopVariable in e.OldItems)
                        {
                            var element = elementLoopVariable;
                            if (regionTarget.ToolBars.Contains(element))
                            {
                                regionTarget.ToolBars.Remove(element as ToolBar);
                            }
                        }
                        break;
                }
            };
        }
        protected override IRegion CreateRegion()
        {
            // Recomendate documentation PRISM Appendix E: Extending Prism 
            return new AllActiveRegion();
        }
    }

    /// <summary>
    /// Version MEF as extension.
    /// </summary>
    [Export(typeof(ToolBarTrayRegionAdapter))]
    [PartCreationPolicy(CreationPolicy.Shared)]
    public class MefToolBarTrayRegionAdapter:ToolBarTrayRegionAdapter
    { 
        [ImportingConstructor]
        public MefToolBarTrayRegionAdapter(IRegionBehaviorFactory regionBehaviorFactory)
            :base(regionBehaviorFactory)
        {
        }
    }
}