Observes changes to properties on underlying items as well as the collection itself

ObservableItemCollection.cs

namespace ViewModels
{
    using System;
    using System.Collections.ObjectModel;
    using System.Collections.Specialized;
    using System.ComponentModel;

    /// <summary>
    /// Represents an observable item collection.
    /// </summary>
    /// <typeparam name="T">The type of the item</typeparam>
    public class ObservableItemCollection<T> : ObservableCollection<T> where T : INotifyPropertyChanged
    {
        /// <summary>
        /// Initializes a new instance of the <see cref="ObservableItemCollection{T}"/> class.
        /// </summary>
        public ObservableItemCollection()
            : base()
        {
            this.CollectionChanged += this.OnCollectionChanged;
        }

        /// <summary>
        /// Called when item property changed.
        /// </summary>
        /// <param name="sender">The sender.</param>
        /// <param name="propertyArgs">The <see cref="PropertyChangedEventArgs"/> instance containing the event data.</param>
        private void OnItemPropertyChanged(object sender, PropertyChangedEventArgs propertyArgs)
        {
            NotifyCollectionChangedEventArgs collectionArgs = new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset);

            this.OnCollectionChanged(collectionArgs);
        }

        /// <summary>
        /// Called when collection changed.
        /// </summary>
        /// <param name="sender">The source of the event.</param>
        /// <param name="collectionArgs">The <see cref="NotifyCollectionChangedEventArgs" /> instance containing the event data.</param>
        private void OnCollectionChanged(object sender, NotifyCollectionChangedEventArgs collectionArgs)
        {
            if (collectionArgs.OldItems != null)
            {
                foreach (object item in collectionArgs.OldItems)
                {
                    (item as INotifyPropertyChanged).PropertyChanged -= this.OnItemPropertyChanged;
                }
            }

            if (collectionArgs.NewItems != null)
            {
                foreach (object item in collectionArgs.NewItems)
                {
                    (item as INotifyPropertyChanged).PropertyChanged += this.OnItemPropertyChanged;
                }
            }
        }
    }
}