Mac OS X 10.7 macmini4,1 Aqua
Run test/closedjava/awt/Component/FlickeringOnScroll manual test. According to the instructions, focus on a scrollbar (you may need to make outermost Frame someway wider) and try to scroll using arrow keys: there will be no response. Note that scrollbars of the Panel are focusable: you may see focusGained/Lost properly on them etc.

Now, should it work on Aqua LaF? If it should, is it really important functionality? I mean, you may lower priority if you can answer that.