Look at the attached movie.

There is some content, which doesn't fit into treeView. So vertical scrollBar appears. I select content with shift+down, after that ctrl+down, and after that ctrl+shift+down. That starts to extand selection, but you cannot see the newly selected nodes.

You may observe ChangeListener or InvalidationListener counters of focusedItem or selectedItem, that selection is being done, but scrolling is not done.

So, I say, that ctrl+shift+down/up (both - I checked) don't scroll to the newly selected items.