title: Tooltip not showing on DataGridViewCheckBoxColumn
body: <p>I am dynamically adding a <code>DataGridViewCheckBoxColumn</code> to my <code>DataGridView</code>.</p>
  
  <p>However, I can't seem to add the tooltip to the checkboxes:</p>
  
  <pre><code>// Method to Populate the DataGrid
      private void PopulateDataGrid(objPatient patient)
      {
          this.uiDocumentDataGrid.DataSource = DataManager.GetDocumentData(patient);
          // Hide unnecessary columns
          this.uiDocumentDataGrid.Columns["Forename"].Visible = false;
          this.uiDocumentDataGrid.Columns["Surname"].Visible = false;
  
          // Add column for selection
          DataGridViewCheckBoxColumn selectedColumn = new DataGridViewCheckBoxColumn();
          selectedColumn.Name = "Selected";
          selectedColumn.HeaderText = "Attach";
          selectedColumn.ReadOnly = false;
          this.uiDocumentDataGrid.Columns.Insert(0,selectedColumn);
  
          // Set columns except checkbox to readonly
          foreach(DataGridViewColumn c in this.uiDocumentDataGrid.Columns)
          {
              if (c.Index &gt; 0)
              {
                  c.ReadOnly = true;
              }
          }
  
          // Refresh the view in case of draw issues
          this.uiDocumentDataGrid.Refresh();
  
          // Add tooltip to each checkbox
          foreach (DataGridViewRow r in uiDocumentDataGrid.Rows)
          {
              r.Cells["Selected"].ToolTipText = "Check this box to select this document.";
          }
  
          // Disable the functionality button if no rows.
          if (this.uiDocumentDataGrid.RowCount == 0)
          {
              this.uiSendButton.Enabled = false;
          }
  
      }
  </code></pre>
  
  <p>No tooltip shows with this method.  Am I missing something obvious?</p>