What you're referring to as "Windows" behavior is actually Mac behavior.
Smalltalk scroll bars were hidden entirely when the mouse pointer was outside a scrollable view. When shown they were on the left, they were proportional and went up/down with a left/right button mouse press. The code for this is probably still in Squeak somewhere - it's certainly how old versions of VisualWorks Smalltalk worked.
Lisa made scroll bars always visible, moved them to the right, made the thumb/elevator non-proportional (users didn't get why it changed size), and added arrows to the ends - and then added page-scroll buttons too. Lisa also came up with the resize corner, rather than resize-by-any-edge or resize-by-explicit-command.
The Mac streamlined this further by getting rid of the page-scroll buttons and making it what happened when clicking in the bar background. Later the Mac also came up with zooming a window to a proper size to fit its contents. (Which isn't the same as maximizing it to fill the screen.)
NeXT moved scroll bars back to the left, put the arrows together at the bottom, made them proportional again, and made clicking in the the bar background scroll to a point.
Mac OS X kept the arrows together and proportionality but matched the positioning of the Lisa and Mac. Scroll-to-point instead of scroll-by-page remained an option in System Preferences though, and holding the option key inverts the behavior.
OS X Lion hid the scroll bars once more, at least for users with touch-scrolling devices like trackpads and the Magic Mouse, and got rid of the arrows.
Smalltalk scroll bars were hidden entirely when the mouse pointer was outside a scrollable view. When shown they were on the left, they were proportional and went up/down with a left/right button mouse press. The code for this is probably still in Squeak somewhere - it's certainly how old versions of VisualWorks Smalltalk worked.
Lisa made scroll bars always visible, moved them to the right, made the thumb/elevator non-proportional (users didn't get why it changed size), and added arrows to the ends - and then added page-scroll buttons too. Lisa also came up with the resize corner, rather than resize-by-any-edge or resize-by-explicit-command.
The Mac streamlined this further by getting rid of the page-scroll buttons and making it what happened when clicking in the bar background. Later the Mac also came up with zooming a window to a proper size to fit its contents. (Which isn't the same as maximizing it to fill the screen.)
NeXT moved scroll bars back to the left, put the arrows together at the bottom, made them proportional again, and made clicking in the the bar background scroll to a point.
Mac OS X kept the arrows together and proportionality but matched the positioning of the Lisa and Mac. Scroll-to-point instead of scroll-by-page remained an option in System Preferences though, and holding the option key inverts the behavior.
OS X Lion hid the scroll bars once more, at least for users with touch-scrolling devices like trackpads and the Magic Mouse, and got rid of the arrows.