[RESOLVED] How to recognize form [X] close?

[memeloo]

I've just found this article on codeproject
http://www.codeproject.com/KB/dialog/CustomDialogs.aspx
and it's quite clear to me. However instead of using ShowDialog I'd like to use a simple Show because it should be a modeless form. I can set the DialogResult to OK or Cancel when I clicked a button and read it in a FormClosed event but how can I set it to Cancel when I clicked on the form's [X] symbol? I just can't figure it out I cannot change the DialogResult in FormClose or FormClosing event because it overwrites this what I've set on button's click.