In Windows 2000, Microsoft introduced a feature called Layered Windows. This introduced desktop composition features that had not been available in previous versions of windows, the most interesting of which was arguably the support for per-pixel transparency. With layered windows, any pixel in a window could be given its own transparency level. This is used for things like the transparent drop shadows you see on some windows, and Outlook uses it to fade new email notifications up and down.[Via IanG on Tap] So, why do I WANT to do this, again? In what possible way is a fuzzy semi-visible version of the underlying video stream useful to me?