One of the new features touted in Leopard:
Scroll Non-Active WindowsScroll any open window, even if it’s not active. Simply position your mouse over the target window and scroll.
http://www.apple.com/macosx/features/300.html
..can be had in XP (NT Based window versions) using this little utility.
Description of the Free app at the site:
The prime purpose of the KatMouse utility is to enhance the functionality of mice with a scroll wheel, offering 'universal' scrolling: moving the mouse wheel will scroll the window directly beneath the mouse cursor (not the one with the keyboard focus, which is default on Windows OSes). This is a major increase in the usefullness of the mouse wheel.Another feature involves the wheel button. Since the wheel button is not consistently used in Windows, KatMouse can use it for a kind of task switching: with a click of the wheel button you can push a window to the buttom of the stack of windows that is your desktop, making a recovered window the active window.
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