title: WPF DataGrid ItemsSource Issue
body: <p>Please let it be known that I am relatively new to WPF. I am creating a new <code>ObservableCollection</code> with the type of my simple data class, and assigning that to the <code>ItemsSource</code> property of my <code>DataGrid</code>. Before I go into my problem here is the code:</p>
  
  <p><strong>XAML</strong>:</p>
  
  <pre><code>&lt;my:DataGrid SelectionMode="Single" SelectionUnit="Cell" Height="113" HorizontalAlignment="Left" Margin="11,22,0,0" Name="addressGrid" VerticalAlignment="Top" Width="213" Background="#FFE2E2E2" AlternatingRowBackground="#FFA4CFF2" BorderBrush="#FF7C7C7C" HorizontalGridLinesBrush="White" PreviewKeyDown="addressGrid_PreviewKeyDown" CellEditEnding="addressGrid_CellEditEnding" BeginningEdit="addressGrid_BeginningEdit" PreparingCellForEdit="addressGrid_PreparingCellForEdit"&gt;
          &lt;my:DataGrid.Columns&gt;
          &lt;my:DataGridTextColumn Header="Name" Width="*" Binding="{Binding Path=Name}"&gt;&lt;/my:DataGridTextColumn&gt;
          &lt;my:DataGridTextColumn Header="Value" Width="3*" Binding="{Binding Path=Value}"&gt;&lt;/my:DataGridTextColumn&gt;
          &lt;my:DataGridTextColumn Header="Index" Visibility="Hidden" Binding="{Binding Path=Index}"&gt;&lt;/my:DataGridTextColumn&gt;
          &lt;/my:DataGrid.Columns&gt;
  &lt;/my:DataGrid&gt;
  </code></pre>
  
  <p><strong>Data Class</strong>:</p>
  
  <pre><code>public class PropertyFields
  {
      public string Name { get; set; }
      public object Value { get; set; }
      public int Index { get; set; }
  }
  </code></pre>
  
  <p><strong>Population</strong>:</p>
  
  <pre><code>ObservableCollection&lt;PropertyFields&gt; propertyList = new ObservableCollection&lt;PropertyFields&gt;();
  for (int i = 0; i &lt; m_pFields.FieldCount - 1; ++i)
  {
     propertyList.Add(new PropertyFields() {Name = m_pFields.Field[i].AliasName, Value = DisplayedValueForRow(i), Index = i});
  }
  
  // Set ItemSource to populate grid
  addressGrid.ItemsSource = propertyList;
  </code></pre>
  
  <hr>
  
  <p><em><strong>More information about the population method:</em></strong> </p>
  
  <p>I am building this solution with ArcGIS framework, so some things are not "System" in ways. </p>
  
  <ul>
  <li><p><code>m_pFields</code> is an <code>IFields</code> interface object that allows me to store spatial layer information</p></li>
  <li><p><code>IFields</code> has a <code>FieldCount</code> property which returns a number of fields in the collection</p></li>
  <li><p><code>DisplayedValueForRow(i)</code> calls another ArcGIS obj method <code>IPropertySet.GetProperty()</code>  and returns the value.</p></li>
  </ul>
  
  <hr>
  
  <p><em><strong>The Problem:</em></strong></p>
  
  <p>Everything is being populated as it should be, but for some odd reason it is re-creating the three columns (Name, Value, Index) again <em>ON TOP</em> of populating the ones created in XAML -- In turn ending up with 2 sets of the same data. I found this to be weird behavior, as I swear I have seen people bind to their grid this way before.</p>
  
  <p>What am I doing wrong?</p>
  
  <h2>Edit</h2>
  
  <p>Thanks to ChrisO's comment, I found out that there is a property called "AutoGenerateColumns" that needed to be turned off. Well I feel like a heel. Thanks!</p>