The Make Transparent action appears in the last generation of Microsoft® operating systems like Windows® 2000/XP/2003/Vista. It allows you making a foreground window look like stained glass so you can see through it to the contents of windows behind it while simultaneously being able to still see the contents of the foreground window as well.
You can choose any transparency level for a particular window ranging from 0% (opaque) to 100% (completely transparent, or invisible).
Hint The Make Transparent action is very handy for working with and between multiple open windows that cannot be sized to fit on the desktop side-by-side. For example, attempting to transcribe something into a Microsoft® Word document from an Internet browser window when they won't both fit on the screen together at the same time.