dialogs: shrink to fit?

[jody <jody xha gmail com>]

Hi
I have dialog which can be expanded to show more input widgets by the
press of a button ("advanced").
Those "advanced" widgets are initially invisible, and when the button
is pressed they are shown, and
the dialog grows correspondingly.
But when i hide the "advanced" widgets again, the dialog retains its large size.

Is there a way to make the dialog shrink to fit, i.e. make it take on
the minimum size such that all visible widgets can be seen?

Thank you
  Jody