title: Win form DataGridView dynamically adding button column
body: <p>I'd like to add a button column dynamically to a DataGridView after it has been populated. 
  The button column is visible after adding it, but when I try to loop through the DataGridView rows, I get a null for the button in each cell.</p>
  
  <pre><code>var buttonCol = new DataGridViewButtonColumn();
  buttonCol.Name = "ButtonColumnName";
  buttonCol.HeaderText = "Header";
  buttonCol.Text = "Button Text";
  
  dataGridView.Columns.Add(buttonCol);
  
  foreach (DataGridViewRow row in dataGridView.Rows)
  {
      var button = (Button)row.Cells["ButtonColumnName"].Value;
      // button is null here!
  }
  </code></pre>