title: DataGridViewComboBoxColumn UI Update Issue
body: <p>i have an issue with the UI update of a DataGridView with a DataGridViewComboBoxColumn.
  When I set the value of a DataGridViewComboBoxColumnCell it works but the UI isn't refreshed.</p>
  
  <p>I tried Invalidate(), Refresh() on the control. Giving it focus and afterwards switch the focus to another control. It is working when I use the same loop in an button event.</p>
  
  <p>My code so far:</p>
  
  <pre><code>        BindingList&lt;String&gt; list = new BindingList&lt;String&gt;();
          list.Add("Value1");
          list.Add("Value2");
  
          DataTable table = new DataTable();
          DataColumn col = table.Columns.Add();
          col.ColumnName = "Key";
          col.DataType = typeof(String);
  
          dataGridView1.DataSource = table;
          table.Rows.Add("Key1");
          table.Rows.Add("Key2");
  
          DataGridViewComboBoxColumn combo = new DataGridViewComboBoxColumn();
          combo.DataSource = list;
          combo.Name = "Value";
          dataGridView1.Columns.Add(combo);
  
          foreach (DataGridViewRow row in dataGridView1.Rows)
          {
              row.Cells["Value"].Value = "Value1";
          }
  </code></pre>
  
  <p>I had similar behaviour with two ZedGraphControls. I implemented dependant zoom and the scale only changed in the plot when I first zoomed manually in both controls. The same happens in my DataGridView, when I change for example the column width manually and the method is called again the UI is refreshed.</p>