title: How can I detect if a JScrollPane's scroll bar changes visibility?
body: <p>I have JScrollPane that contains some images in a horizontal row. If the row of images is too long for the view port, the JScrollPane shows a scroll bar, reducing the height of the view port. I'd like to resize the images to fit the view port. How can I detect that the view port changed its size?  Unfortunately, registering change event handlers doesn't seem to work. </p>