C#

• System.Action is built-in delegate, it's defined as
  public delegate void Action()
  If you replace GetMe with Action, you will get an error in two cases.
  
• At the run-time, the conversion will fail, and si will be null.
  
• If you replace
  si = _call as System.ComponentModel.ISynchronizeInvoke;
  with
  si = (System.ComponentModel.ISynchronizeInvoke)_call;,
  both generic and non-generic will fail.
  

dataGridView1.Columns[3].ReadOnly = true;

private void button1_Click(object sender, EventArgs e)
{
    dataGridView1.CurrentCell = dataGridView1[3, 0];
}

private bool IsValidColumn1Response(DataGridViewCell dgvCell)
{
    return (dgvCell.Value == null) ? false : dgvCell.Value.ToString() == "Home";
}

private bool IsValidColumn2Response(DataGridViewCell dgvCell)
{
    return (dgvCell.Value == null) ? false : dgvCell.Value.ToString() == "Business";
}

private void dataGridView1_SelectionChanged(object sender, EventArgs e)
{
    // base on code from http://stackoverflow.com/questions/751981/bypass-read-only-cells-in-datagridview-when-pressing-tab-key
    DataGridView dgv = sender as DataGridView;
    if (dgv != null)
    {
        // **NOTE** when this event fires, CurrentCell is the cell being moved FROM.
        DataGridViewCell currentCell = dgv.CurrentCell;
        if ((currentCell != null) && (currentCell.ColumnIndex == 1))
        {
            int nextRow = currentCell.RowIndex;
            int nextCol = currentCell.ColumnIndex;
            if (this.IsValidColumn1Response(currentCell))
            {
                dgv[nextCol + 1, nextRow].Value = "N/A";
                nextCol += 2;
            }
            DataGridViewCell nextCell = dgv.Rows[nextRow].Cells[nextCol];
            if (nextCell != null && nextCell.Visible)
            {
                dgv.CurrentCell = nextCell;
            }
        }
        else if ((currentCell != null) && (currentCell.ColumnIndex == 0))
        {
            int nextRow = currentCell.RowIndex;
            int nextCol = currentCell.ColumnIndex;
            if (this.IsValidColumn2Response(dgv[currentCell.ColumnIndex + 2, currentCell.RowIndex]))
            {
                nextCol++;
                dgv[nextCol, nextRow].Value = "N/A";
            }
            DataGridViewCell nextCell = dgv.Rows[nextRow].Cells[nextCol];
            if (nextCell != null && nextCell.Visible)
            {
                dgv.CurrentCell = nextCell;
            }
        }
    }
}