databinding multiple fields in UI not updating - winforms

Question

I have a winform that contains a bindingsource the data source of which is a typed dataset. I have bound in the designer two text boxes to the same column. When I update either textbox the DataRow column in the DatSet is correctly updated however the other textbox value on the form is not updated.
What am I missing? How do I get the databindings to update the second textbox?
NOTE: this is a simplified example I need to do this because in the real application because one control is editable by the user the other is the input into a composite control for calculations.
// Taken from InitializeComponent()
this.productsBindingSource.DataMember = "Products";
this.productsBindingSource.DataSource = this.dataSet1;
this.textBox1.DataBindings.Add(new Binding("Text", this.productsBindingSource, "UnitsInStock", true, DataSourceUpdateMode.OnPropertyChanged));
this.textBox2.DataBindings.Add(new Binding("Text", this.productsBindingSource, "UnitsInStock", true, DataSourceUpdateMode.OnPropertyChanged));
// Taken from Form Load Event
DataSet1TableAdapters.ProductsTableAdapter adapter = new DataSet1TableAdapters.ProductsTableAdapter();
adapter.Fill(dataSet1.Products);

Answer 1

There's an article on MSDN which might help - see How to: Ensure Multiple Controls Bound to the Same Data Source Remain Synchronized
Essentially you need to set up an event handler for the BindingSource's BindingComplete event (as you have done, you need to have FormattingEnabled set to True for this to work)
Then, in the BindingComplete event handler, you have this code:
private void productsBindingSource_BindingComplete(object sender, BindingCompleteEventArgs e)
{
// Check if the data source has been updated,
// and that no error has occured.
if (e.BindingCompleteContext == BindingCompleteContext.DataSourceUpdate && e.Exception == null)
{
// End the current edit.
e.Binding.BindingManagerBase.EndCurrentEdit();
}
}

Answer 2

So my solution was to Implement INotifyPropertyChanged on the Typed Data Row class as it is exposed as a partial class by the designer this was fairly straight forward and then set the data source of the bindingsource to be the data row itself.
public partial class MyDataRow : INotifyPropertyChanged
{
public void AddEventHandler()
{
this.Table.ColumnChanged += new System.Data.DataColumnChangeEventHandler(Table_ColumnChanged);
}
void Table_ColumnChanged(object sender, System.Data.DataColumnChangeEventArgs e)
{
OnPropertyChanged(e.Column.ColumnName);
}
#region INotifyPropertyChanged Members
public event PropertyChangedEventHandler PropertyChanged;
private void OnPropertyChanged(string propertyName)
{
if (PropertyChanged != null)
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
#endregion
}
Code to data bind
MyDataRow row = <Get Current Row>;
row.AddEventHandler();
bindingSource1.DataSource = row;