There are often times when you are working in one application and looking up information in a second at the same time. Often you find that the screen just isn't quite big enough to display all of what you want in both applications so you hide the controls at the top of one application under the bottom of the data window in the other.
Now if you were running any other operating system then whenever you wanted to scroll the second application window you'd have to swap to that application, scroll the window, then swap back, probably losing your place in the first application in the process.
With OS/2 you can scroll the second window without losing your current focus in the first window. To do this you hold down the Ctrl key while you click and drag the centre button of the scrollbar in the back window. When you do this that window is scrolled but the current focus stays with the other window and you don't lose your place.
This article written by Stephen Chapman, Felgall Pty Ltd.