I thought I was pretty well versed in the use of my Mac, but today I ca across something I never knew (shame on me) I discovered on the Mac Kindergarten site.
Background scrolling!
You can scroll in windows that are currently inactive. Simply mouse over the window (resist that clicking urge) and simply scroll.
Now if you press the Apple (command ) key before you click into the window’s top you can even move it without making it active. Neat