Forms: Making footer visible hides Detail section

[John]

I have a form (popup) that shows a small number of fields in the
Detail section. The footer is not visible on open.

When the user clicks a button on the detail section, the footer
becomes visible. The problem is, the detail gets "hidden" because it's
essentially replaced by the footer.

Question:
How can I get the form to dynamically grow to show both the detail and
footer sections after the mentioned button is pressed?

Thank you....