.NET Windows Forms - intercepting the Close X event

Question

This must be a dumb question, but I cannot figure it out. I also cannot use the designer because coders before me managed to throw GUI and logic all in one, so now it is confused. I've got to do it the old school way.

I have a Form which can be closed in 3 ways: Close button, File / Close menu, and the X icon. I want them all to do the same thing. Intercepting the button and the menu events is easy. In fact, both are hooked up to an onCloseConfig method. Btw, is there a better name for this method?

private void onCloseConfig(object sender, System.EventArgs e)
{
    if (! m_configControl.Modified)
    {
        Application.Exit(); // Or should it be this.Close();
    }
    ....
    // Else present a dialog, ask if they want to save.
}

So, to intercept the X I tried: this.FormClosing +=new FormClosingEventHandler(this.onCloseConfig); I believe this is what causes an infinite loop. I do not want that :) FormClosed is another option, but it seems too late. I just want to intercept the fact that the X was clicked, not the fact that the form is closing.

Answer 1

I think you do want form closing, the thing you may be missing is to check the reason for closing and only cancel it if it is from the user e.g.

private void my_FormClosing(object sender, FormClosingEventArgs e)
{
  if (e.CloseReason == CloseReason.UserClosing)
  {
    e.Cancel = true; //I'm sorry Dave, I'm afraid I can't do that.
  }
}

to hide the 'X' set Form.ControlBox = false, but this will get rid of min/max as well.

Answer 2

Create a separate method for the button/menu close:

private void myButton_Click(object sender, EventArgs e)
{
    this.Close();
}

private void myMenuButton_Click(object sender, EventArgs e)
{
    this.Close();
}

private void myForm_FormClosing(object sender, FormClosingEventArgs e)
{
    if (m_configControl.Modified)
    {
        var result = MessageBox.Show("Name Of Application", "Would you like to save before closing?", MessageBoxButtons.YesNoCancel);
        if(result == DialogResult.Yes)
            //Save here
        else if(result == DialogResult.Cancel)
            e.Cancel = true;
    }
}

Or, you can disable the close-button ("X") altogether by setting this.ControlBox = false