Apple leaks new scroll bar UI details in Mac OS X 10.7 Lion
Lion's contextual scroll bars
The higher resolution image of Mission Control isn't entirely consistent with the apps Apple demonstrated however. Craig Federighi, Apple's vice president of Mac OS X engineering, demonstrated a brief glimpse of Mac OS X Lion features where a mishmash of scroll bars intermingled.
Incidentally, Federighi formerly led Apple's WebObjects server development before leaving the company in 1999 to serve as the chief technology officer for Ariba. Last year, Federighi was recruited back to Apple by Bertrand Serlet, the company's senior vice president of software engineering. Back in the 90s, Federighi worked as a protege of Serlet at Apple and before that at NeXT, where he served as a key architect of the company's object-oriented frameworks for enterprise application development.
In his sneak peak at Mac OS X Lion, Federighi first opened the new Mac App Store, which at launch displayed no scroll bar, despite having more content than could fit in the window. However, after scrolling into the app listings, a dark grey iOS-style menu bar appeared with no scroll arrows nor any menu bar track. After a moment of inactivity, the scroll bars vanish again. This appears to be the new look of scroll bars in Lion, or at least the preferred option.
The Mac App Store is also unique in that it centers the window button controls with the tool bar buttons, eschewing the use of a window title bar at all. Presumably, if you have the Mac App Store open, you don't need a line of text telling you that's what it is. This divergence from the Mac OS X human interface guidelines is interesting, and again, tends to result in a more iPad-like experience, despite the app existing as a free floating window on the desktop and not a full screen app.
In fact, the Mac App Store appears to be designed not to enter full screen app mode, as its green Zoom button is dimmed. In the presentation, Federighi also explicitly noted in passing that the green button is now considered a full screen app button rather than the "zoom to the largest window size that makes sense" that it always has been on the Mac.
On page 3 of 3: Still a work in progress.