title: change value of one column in datagrid by changing another
body: <p>I can change the value of quanity column in data grid, but i cant seem to update the total price column of the same row using celleditending event this is my xaml</p>
  
  <pre><code>&lt;DataGrid AutoGenerateColumns="False" EnableColumnVirtualization="False" EnableRowVirtualization="False" IsSynchronizedWithCurrentItem="True" SelectedItem="{Binding SelectedItem}" Grid.Row="3" Grid.ColumnSpan="2" Name="DataGrid1" ItemsSource="{Binding DataGridItemsSource, Mode=TwoWay, IsAsync=True}" Margin="10,10,10,10" PreviewKeyDown="DataGrid1_PreviewKeyDown" SelectionChanged="DataGrid1_SelectionChanged" CellEditEnding="DataGrid1_CellEditEnding" BeginningEdit="DataGrid1_BeginningEdit" &gt;
      &lt;DataGrid.Columns&gt;
          &lt;DataGridTextColumn Header="Item Name" IsReadOnly="True" Binding="{Binding Path=ItemName}" Width="*"&gt;&lt;/DataGridTextColumn&gt;
          &lt;DataGridTextColumn Header="Item Price" IsReadOnly="True"  Binding="{Binding Path=ItemPrice}" Width="*"&gt;&lt;/DataGridTextColumn&gt;
          &lt;DataGridTextColumn x:Name="QuantityColumn" Header="Quantity" IsReadOnly="False"  Binding="{Binding Path=Quantity, Mode=TwoWay}" Width="*"&gt;&lt;/DataGridTextColumn&gt;
          &lt;DataGridTextColumn  Header="Total Price" IsReadOnly="True" Binding="{Binding Path=TotalPrice, Mode=TwoWay}" Width="*"&gt;&lt;/DataGridTextColumn&gt;
      &lt;/DataGrid.Columns&gt;
  &lt;/DataGrid&gt;
  </code></pre>
  
  <p>And this is my c# WPF for</p>
  
  <pre><code>private void DataGrid1_CellEditEnding(object sender, DataGridCellEditEndingEventArgs e)
  {
      DataGrid dg = sender as DataGrid;
      AddItem row = (AddItem)dg.SelectedItems[0];
  }
  </code></pre>
  
  <p>From this i can easily get the new value of quantity but cant seem to figure out how to update the totalprice column of my datagrid.itemsource of the same row. any help will be appreciated</p>
  
  <pre><code>public class AddItem : INotifyPropertyChanged
          {
              public event PropertyChangedEventHandler PropertyChanged;
              public string ItemName { get; set; }
              public float ItemPrice { get; set; }
              public string Price { get; set; }
              public int Quantity { get; set; }
              public decimal TotalPrice { get; set; }
              public int Size
              {
                  get { return Quantity; }
                  set
                  {
                      Quantity = value;
                      if (PropertyChanged != null) PropertyChanged(this, new PropertyChangedEventArgs("Size"));
                  }
              }
          }
  </code></pre>
  
  <p>This is for the Additem what am i missing</p>