My scrolling thumbnail panel work great but I want to ad some
extra functionality. I have two arrows above the panel. One for
left and one for right.
Once the panel gets all the way to the left I want the left
arrows alpha value to be set at 0 and once it begins to scroll
right it needs to be visible again.
here is my attempt. Only the left arrows alpha is at 0 since
beginning xPos is 0.