I always wondered why people couldn't get the mouse scrolling tutorial to work (even when the frame size was larger than the application size) and I finally figured out why.
Basically the code for scrolling right indicates the left frame edge as a condition. I thought I would save time if I followed the tutorial verbatim, but it didn't work. It was pretty frustrating for about ten minutes, but to a beginner who has no idea what they are doing, this could be extremely frustrating when they have followed the instructions, yet the scrolling fails to work.
Anyway, I think it should be updated right away or temporarily taken down or something. I didn't check the other part of the tutorials, so maybe just the mouse part has some problems.