[Self answered, but posted as it may be useful to others]

Is there a way to have one form "replace" another? I want to have a login form, and
then once they have logged in, to change the "main" form to be the working form.
This would sort of be a "stack" of forms, as I'd want to be able to return later.

At the moment, if I click my login button and do the NewForm.ShowModal, the form
appears overlaid on the main form. I realise I can control this a bit, but the
original is there still.

Okay, I just realised, while about to quote from the help (the usage for TForm is
particularly good), that this is entirely possible. Self.Hide and using the OnClose
to show it again.

What a brilliant system this is.

/Matthew Jones/