/// <summary>
 /// Not supported.
 /// </summary>
 /// <param name="item">The object to locate in the <see cref="T:System.Collections.Generic.ICollection`1"/>.</param>
 /// <returns>
 /// Always false.
 /// </returns>
 public bool Contains(VirtualizingCollectionDataWrapper <T> item)
 {
     foreach (VirtualizingCollectionDataPage <T> page in _pages.Values)
     {
         if (page.Items.Contains(item))
         {
             return(true);
         }
     }
     return(false);
 }
 /// <summary>
 /// TODO
 /// </summary>
 /// <param name="item">The object to locate in the <see cref="T:System.Collections.Generic.IList`1"/>.</param>
 /// <returns>
 /// TODO
 /// </returns>
 public int IndexOf(VirtualizingCollectionDataWrapper <T> item)
 {
     foreach (KeyValuePair <int, VirtualizingCollectionDataPage <T> > keyValuePair in _pages)
     {
         int indexWithinPage = keyValuePair.Value.Items.IndexOf(item);
         if (indexWithinPage != -1)
         {
             return(PageSize * keyValuePair.Key + indexWithinPage);
         }
     }
     return(-1);
 }
 /// <summary>
 /// Not supported.
 /// </summary>
 /// <param name="item">The object to remove from the <see cref="T:System.Collections.Generic.ICollection`1"/>.</param>
 /// <returns>
 /// true if <paramref name="item"/> was successfully removed from the <see cref="T:System.Collections.Generic.ICollection`1"/>; otherwise, false. This method also returns false if <paramref name="item"/> is not found in the original <see cref="T:System.Collections.Generic.ICollection`1"/>.
 /// </returns>
 /// <exception cref="T:System.NotSupportedException">
 /// The <see cref="T:System.Collections.Generic.ICollection`1"/> is read-only.
 /// </exception>
 public bool Remove(VirtualizingCollectionDataWrapper <T> item)
 {
     throw new NotSupportedException();
 }
 /// <summary>
 /// Not supported.
 /// </summary>
 /// <param name="index">The zero-based index at which <paramref name="item"/> should be inserted.</param>
 /// <param name="item">The object to insert into the <see cref="T:System.Collections.Generic.IList`1"/>.</param>
 /// <exception cref="T:System.ArgumentOutOfRangeException">
 ///     <paramref name="index"/> is not a valid index in the <see cref="T:System.Collections.Generic.IList`1"/>.
 /// </exception>
 /// <exception cref="T:System.NotSupportedException">
 /// The <see cref="T:System.Collections.Generic.IList`1"/> is read-only.
 /// </exception>
 public void Insert(int index, VirtualizingCollectionDataWrapper <T> item)
 {
     throw new NotSupportedException();
 }
 /// <summary>
 /// Not supported.
 /// </summary>
 /// <param name="item">The object to add to the <see cref="T:System.Collections.Generic.ICollection`1"/>.</param>
 /// <exception cref="T:System.NotSupportedException">
 /// The <see cref="T:System.Collections.Generic.ICollection`1"/> is read-only.
 /// </exception>
 public void Add(VirtualizingCollectionDataWrapper <T> item)
 {
     throw new NotSupportedException();
 }