Just a minor nitpick, but we aim at perfection, right?
Open elementary_test -to "Efl.Ui.Scroller Simple". The viewport scrolls to the bottom and the "down" arrow button in the right scrollbar is disabled. This is fine.
Now start clicking on the "up" arrow. You will see the "down" button is not reenabled on the first click. This is wrong.
Keep clicking "up". Once the "down" button is enabled, start clicking it until it gets disabled. This should mean that there is no more content (we reached the end of the scrollbar), but this is not true. You can still scroll down a bit more by dragging the thumb or by using thumbscrolling.