Winform Alt F4 exit YesNo dialog

Question

 Hello, I want to add in a feature.

When exit button is clicked, it'll give Yes or No option.

If Yes, application closes, if No, nothing happens. 

I have no problem with the coding below when it comes to "Click",

but when I press "Alt F4", program closes even if I click "No"

 

 

private void exitButton_Click(object sender, EventArgs e)

{

    while(MessageBox.Show("Exit app?","Exit message",MessageBoxButtons.YesNo) == DialogResult.Yes)

    {

       this.Close();

     }

       //If "No", MessageBox closes

}

 

//////////////////////////////////////////////////////////////////////////////////

 

private void MainForm_KeyDown(object sender, KeyEventArgs e)

{ 

    if (e.Alt && e.KeyCode == Keys.F4)

    {

       exitButton_Click(null, null);

     }

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