For nearly three decades, Macintosh windows were topped with a menu bar, whether a program was open or not.
For half that time, to select something in a Macintosh menu, a user had to click, drag the mouse down, and unclick to select. For instance, to save a document, the user would have to hover the cursor over "File," press the mouse button down, drag the mouse down to "Save" and then unclick on "Save."
According to Apple's "Macintosh Human Interface Guidelines" from 1995, it was one of the few times that a selection was made by pressing a button and lifting a finger off the mouse rather than clicking.
Apple eventually changed its mind with the release of OS 8 in 1997, and Mac menus began to function like those in Windows. With last year's release of OS X Lion, Apple even did away with the menu entirely.
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