Disable the Close box on a form

I have used this in the past and have also posted as one of my tip tricks :-}
One tip trick that I still like with CreateParams is changing

parms.ClassStyle |= 0x200;

to

parms.ClassStyle = this.Handle.ToInt32();

which will render the form invisible which is much easier than overriding

SetVisibleCore(bool value)

because you then have to have another bool value to ensure the FormLoad Event is called.