Apple leaks new scroll bar UI details in Mac OS X 10.7 LionApple's chief executive Steve Jobs specifically highlighted a few new user interface changes coming in the next release of Mac OS X, but his presentation also revealed additional subtle but significant changes to how scroll bars work in the new Mac user interface.
Jobs' presentation focused on a few incremental evolutions, ranging from a more iPad-like implementation of full screen apps (Preview and iPhoto, specifically) to an enhanced version of Exposé named "Mission Control" that better integrates with the Dashboard and Desktop views, and also does a better job of clustering apps' windows together.
Apps' clustered windows in Mission Control behave more like groups of photos on the iPad, another example of the cross pollination going on between iOS and the Mac OS X desktop. The new interface also blends Spaces' virtual desktops into the user interface more cohesively in a way that will likely be accessible to a wider audience.
The concept of full screen apps goes beyond the "heads up display" full screen views the company has been experimenting with. Rather than presenting a single document full screen, with a normal menu bar, navigation controls and tool bar palettes that slide into view when the user mouses over the top and bottom of the screen, the new full screen view of iPhoto 11 presents a simplified, windowless interface with an iPad-like toolbar that's always visible. There's also subtle grey scroll bars.
What Jobs didn't address: vanishing scroll bars
Curiously, Jobs didn't make any mention of another significant interface element that appears to be undergoing a rather radical rethinking in Mac OS X Lion: the scroll bar, which now appears to vanish whenever its not in active use.
Jobs similarly presented iTunes 10 recently without even mentioning the rather radical vertical repositioning of its title bar window controls, as if such a change were not that big of a deal. To many Mac users however, any changes to the user interface guidelines are very noteworthy, and often even arouse controversy.
Screen shots taken during the "Back to the Mac" presentation--and particularly enhanced shots Apple has provided to the media--reveal that apps modernized by Apple as part of Lion do not present scroll bars until the user begins scrolling, similar to the iOS.
Specifically, the Mission Control screen shot (below, click to download the full size graphic) indicates that Mac OS X Lion's new Mail, iCal, Mac App Store, Safari, and the iWork Pages app all present their documents and content without active scroll bars at all.
On page 2 of 3: Lion's contextual scroll bars.