OS X Lion Safari and Chrome's Vertical Scrollbar (overlay versus next to content)

Question

What determines how the scrollbar is rendered in OS X Lion? On my home and work machine, I see the scrollbar next to the content like this:

A co-worker, also running Lion has that same scrollbar overlaid ontop of the content (partially transparent), rather than in a "column" next to the content.

What determines which of these you get? Only difference I can figure out is because he's using a magic mouse, and I'm using a Logitech. Systems preferences for scrolling (in the general pref), we both have "Show scrollbars" set as "Automatically based on input device."

Answer 1

That's your reason right there, you are using a traditional mouse, and so you get the traditional scrollbar, it should always be on view. Your friend is using a touch input device, and like with trackpad users this does not rely on accurate positional use of the cursor, and so the scrol bars dissapear unless active scrolling is happening, as they do not need to be seen for a target, and when they do show they overlay so as not to cause a nasty screen artifact (namely an 8 pixel wide scroll bar flashing in and out of existance, possibly causing screen repagination etc)