By AppleInsider Staff

Published: 03:00 PM EST (12:00 PM PST)

Apple is finally letting go of old windowing conventions that date back to the original Macintosh, allowing users in Mac OS X 10.7 Lion to fluidly interact with windows any way they like.

Back in 1984, Apple had to bundle new Macs with instructions on how to use a mouse. Today, users don't need the same kind of hand-holding, although the company now includes videos within System Preferences to demonstrate how various multitouch gestures work.

Apple has increasingly stripped the Mac OS Human User Interface Guidelines of unnecessary chrome designed to show them how to do things (like resize windows, or reposition information within a window) that are now easier to discover, thanks to smoothly animated graphical transitions.

Apple's chief executive Steve Jobs demonstrated some of the new features of Lion back in September.

Overlay scrollbars

Many of these advances were pioneered by iPhone's iOS, including the removal of full sized scroll bars that tend to take up a significant strip of valuable real estate, particularly on mobile devices.

As was only hinted at previously, Mac OS X Lion will similarly draw only subtle "overlay scrollbars" when necessary, allowing them to fade away to avoid consuming area within windows.

As demonstrated in the video below, Lion's scrollbars can be directly interacted with using the pointer while they are visible, a trick that isn't possible on iOS.

Flexible window resizing

The Mac now gains the ability to resize windows from any edge or corner, similar to features exposed over twenty years ago by Jobs' NeXTSTEP operating system, but which were removed from Mac OS X in order to preserve the look and feel of the original Mac UI.

Lion exposes flexible window resizing without resorting to resize controls however; the edges of windows remain borderless, with only a pointer change indicating the directions a window boundary can be resized. Movie on page two.

Update: A developer reports that window resizing also supports standard modifier keys, so holding Shift while resizing a window from any edge constrains the window resizing to its existing aspect ratio, while holding Option resizes the window from its center point.

On page 2 of 2: Enhanced Finder features.