title: DataGridView with a checkbox with default value checked
body: <p>I have a dataGridView in a Winform, I added to the datagrid a column with a checkbox using  a code I saw here : </p>
  
  <pre><code>    DataGridViewCheckBoxColumn column = new DataGridViewCheckBoxColumn();
      {
          column.HeaderText = "Export";
          column.Name = "Export";
          column.AutoSizeMode =
              DataGridViewAutoSizeColumnMode.DisplayedCells;
          column.FlatStyle = FlatStyle.Standard;
          column.CellTemplate = new DataGridViewCheckBoxCell(false);
          column.CellTemplate.Style.BackColor = Color.White;
      }
  
      gStudyTable.Columns.Insert(0, column);  
  </code></pre>
  
  <p>this works but I want the checkBox to be checked as a default saw I added :</p>
  
  <pre><code>    foreach (DataGridViewRow row in gStudyTable.Rows)
      {                
          row.Cells[0].Value = true;
      }
  </code></pre>
  
  <p>but the checkbox col is still unchecked. I'm using a collection as my data source and I change the value of the col after I added the data source.</p>