if (checkBox1.Checked)
            {
                MessageBox.Show(checkBox1.Text.ToString());
            }

// ListBox method to select an item...
public void SetSelected(int index, bool value);
public ListBox.SelectedObjectCollection SelectedItems { get; } // to see all items selected...
// and, to capture when the selection is changing:
public event EventHandler SelectedIndexChanged;
 
// RadioButton method to get/set state:
public bool Checked { get; set; }
// and, to capture when the state has been changed:
public event EventHandler CheckedChanged;
 
// ComboBox methods to select item:
public override int SelectedIndex { get; set; }
public object SelectedItem { get; set; }
// and, to capture when the selection has changed:
public event EventHandler SelectedIndexChanged;