Computers are for solving problems, and the degree to which they are successful depends on the margins they allow to be crossed by increasing productivity. That is, a computer is successful if it enables you to do something that you couldn't do otherwise because it would take too much time. To give a concrete example, computers allowed you to cross the barrier to reading this document, because you did not have to write a letter to me requesting it, wait for me to make a copy (with a pen), and then mail you the copy. The analog way (with the pen) is beyond your cost (in time, energy, price, etc.) margin.
Increasing the number of margins that a computer allows you to cross increases the total number of things you can accomplish. That is, if you can use a computer more efficiently, you can use it to do more things because those things will fall below the margin of worth-doing-for-the-time-required. For example, if you could easily paste text without formatting with a hotkey, you would paste text more often (for example, into Word), because it wouldn't be such a pain to fix the formatting on all your text. You could refer to your old documents more often if you could find them quickly. Time is a limited resource, and because of this scarcity (and therefore rationing), you could do things more with computers (and therefore more things in general) if you could do those things faster. They would fall within your margins. They would be worth it. This documents explains how to tailor your computer use so you can do more things.
Window Control (updated 2011-10-29)