private void RemoveSelectedItem(object obj)
 {
     for (int i = SelectedItemsInListBox.Count; i-- > 0;)
     {
         ItemViewModel item = SelectedItemsInListBox[i];
         if (item.IsSelected)
         {
             SelectedItemsInListBox.RemoveAt(i);
         }
     }
 }
        public void RemoveClickedItem(object obj)
        {
            System.Windows.Controls.TextBlock itemTextBlock = obj as System.Windows.Controls.TextBlock;
            if (itemTextBlock == null)
            {
                return;
            }

            foreach (KeyValuePair <int, string> item in AvailableItemList)
            {
                if (item.ToString() == itemTextBlock.Text)
                {
                    SelectedItemsInListBox.RemoveAt(item.Key);
                }
            }
        }