title: Add item to DataGridViewComboBoxColumn
body: <p>I have a DataGridView and I change one column to a DataGridViewComboBoxColumn. And I can edit the Items to put some data in it and it works.</p>
  
  <p>But I want to put the Items in program, therefore, I try to use dataGridView1.Columns["drop_column"]. But it doesn't have a Items </p>
  
  <p>I found this article but it's to create a new column but I already have a column <a href="https://stackoverflow.com/questions/1357389/add-items-to-datagridviewcomboboxcolumn-in-datagridview-during-runtime">Add items to DataGridViewComboBoxColumn in DataGridView during runtime</a>.</p>
  
  <p>Update: thanks to Ginosaji and Dona, I add a cast and it works now.</p>
  
  <pre><code>((DataGridViewComboBoxColumn)dataGridView1.Columns["drop_column"]).Items.Add("1");
  ((DataGridViewComboBoxColumn)dataGridView1.Columns["drop_column"]).Items.Add("2");
  ((DataGridViewComboBoxColumn)dataGridView1.Columns["drop_column"]).Items.Add("3");
  </code></pre>