C#

private void CancelButton_Click(object sender, System.EventArgs e)
{
    this.DialogResult = DialogResult.Cancel;
    this.Close();
}

protected override void OnClosing(CancelEventArgs e)
{
    if(this.DialogResult == DialogResult.None)
    {
        //Comes from X
    }
    else if(this.DialogResult == DialogResult.Cancel)
    {
        //Comes from CancelButton
    }

    base.OnClosing (e);
}

Luc Pattyn wrote:

I dont think it will work your way

Luc Pattyn wrote:

Windows already sets DialogResult to Cancel on
hitting the Close box.

Luc Pattyn wrote:

And, we have had a difference of opinion on this before: one should not go against
such conventions.

Martin# wrote:

Have you tested it?

Martin# wrote:

Help me with long-term memory, when was that

Luc Pattyn wrote:

Yes.

Luc Pattyn wrote:

IIRC it was about changing the behavior of a group of radio buttons;

Luc Pattyn wrote:

my point was and is
if it looks like standard controls, it should behave like them too.

Martin# wrote:

So why do we have different results than?

Luc Pattyn wrote:

we have different systems

Luc Pattyn wrote:

there is a misunderstanding somewhere

private void CancelButton_Click(object sender, System.EventArgs e)
{
    this.DialogResult = DialogResult.Cancel;
    this.Close();
}

protected override void OnClosing(CancelEventArgs e)
{
    if(this.DialogResult == DialogResult.None)
    {
        //'X' was pressed
    }
    else if(this.DialogResult == DialogResult.Cancel)
    {
        //CancelButton was Pressed
    }

    base.OnClosing (e);
}

Luc Pattyn wrote:

one of us is wrong (but who then?)

Luc Pattyn wrote:

The last post from the OP seems to hint towards the third possibility, doesnt it ?

Luc Pattyn wrote:

Maybe/probably the "Close Box implies Cancel result" only applies to dialogs (forms shown with
ShowDialog) where it matters most, and not to regular forms, shown with Show() ?

Luc Pattyn wrote:

If so, you probably did the wrong experiment

Luc Pattyn wrote:

and hence your tip does not work, whereas setting it to something else
such as DialogResult=Yes; would work

(but it would then violate the GUI conventions, as I keep telling you).