How to detect Help button press in Windows Forms MessageBox?

I have a message box with 3 buttons: Yes, No, Help:

var result = MessageBox.Show("text", "title",
                MessageBoxButtons.YesNo,
                MessageBoxIcon.Warning,
                MessageBoxDefaultButton.Button1,
                true);

I can detect if Yes/No buttons where clicked something like this:

if(result == DialogResult.Yes)
    // some actions

How I can detect that Help button was 开发者_C百科pressed and execute my own code?

You want to handle the Form's HelpRequested event. See the example in the help topic.

public static DialogResult Show(
    string text,
    string caption,
    MessageBoxButtons buttons,
    MessageBoxIcon icon,
    MessageBoxDefaultButton defaultButton,
    MessageBoxOptions options,
    bool displayHelpButton
)