this will never work (it's scrollPane.setViewportView(contentPane) - excuse typos)
this is likely to be the problem:
> The JFrame content pane is a simple JPanel with no layout.
the basics of a scrollpane is that the preferredSize of the component in the viewport
must be bigger than the preferredeSize of the scrollpane - i.e. if the panel has no layout,
then it has no preferredSize = you must set it.