Override standard close (X) button in a Windows Form

Question

How do I go about changing what happens when a user clicks the close (red X) button in a Windows Forms application (in C#)?

Answer 1

You can override OnFormClosing to do this. Just be careful you don't do anything too unexpected, as clicking the 'X' to close is a well understood behavior.

protected override void OnFormClosing(FormClosingEventArgs e) {     base.OnFormClosing(e);      if (e.CloseReason == CloseReason.WindowsShutDown) return;      // Confirm user wants to close     switch (MessageBox.Show(this, "Are you sure you want to close?", "Closing", MessageBoxButtons.YesNo))     {     case DialogResult.No:         e.Cancel = true;         break;     default:         break;     }         }