The watch stayed armed when the form arrived while the focus was off the close button, so a
later change in the body pulled the focus off a close button the user went back to. It now
disarms on arrival and re-arms only when the focus is taken away.
Modal takes a required initialFocus (field / close / action), a field that
loads late takes the focus while it still rests on the close button, and
ModalFooter portals a dialog's commit row under the scrolling body from any
depth. The header and footer fades follow the body's scroll timeline, and the
viewport's interactive-widget=resizes-content keeps the footer above an
on-screen keyboard.
peter