If one would change minViewportWidth without changing prefViewportWidth, this would not affect ScrollPane, until prefViewportWidth is changed (no matter how much).

Steps to reproduce:
1) Download either .java file from attachements or netbeans project
2) Run it
3) Move first (prefViewportWidth) and third (minViewportWidth) slider, so that the third slider is ahead of first
4) Play around with the third slider, see there's no change on the width, despite the fact it should be
5) Touch (move a little bit) the first slider and you'll see the change in the width.