Changing L&F shouldn't change the position of Scrollbar thumb
Steps to reproduce:
   a) Open SwingSet2
   b) Go to JList demo.
   c) Make sure first list have last visible Item "TeraWorks", Second
      list "Analog" and third list "Concepts". i.e there last items
   d) Now change to some other L&F and see last visible items of
      list changes. It is because you will notice that Scrollbar thumb
      is moved up.