I'm unaware if this is a super-secret Microsoft formula, but it sure as heck is interesting.
There are several aspects of Windows Aero that are interesting, but the main priority is,
How does Windows Aero draw transparent glass? That is, drawing a transparent and blurred surface on the titlebar and around the windows.
First of all, how does Windows Aero draw the borders of windows? Since Windows is an operating system, it has to be optimized for computers ranging from a variety of spefications.
Let's pretend we're running a game with a blur shader programmed in. In most cases with older specifications, the framerate is likely to decrease, but it doesn't seem like the case with Windows - an operating system? I guess you could say, sure, everytime the user changes the wallpaper, create a blurred copy of the wallpaper and have each window draw a section of the wallpaper.
But Windows Aero, is more dynamic than that with it's drawing mechanisms. Let's say we move a window under an overlapping window, and the window under will move and display blurred on the overlapping window's border at a framerate not too different.
How does it actually work? Does Windows actually create a new blurred image everytime the screen updates, for display on the window's borders? Does only the mask of the borders get blurred, but even then, blurring a border more than e.g. 1024px would still sound rather performance-hungry?
Thank you in advance!