I've noticed that since I installed Mavericks, images no longer want to scroll via mouse wheel when I open them in Preview. On ML, I could open 20 or 30 images, and just effortlessly scroll through them with the mouse wheel. On Mavericks, though, it forces me to click each one and change individually. Scrolling on the image does nothing, and scroll in the sidebar only makes it scroll down to reveal more thumbnails. Is there a setting I can change, or is this normal behavior? It seems like a real step backwards.