Why are window managers all the same? Sure, programming interface is different, so is rendering, and other desktops. However, windows are always square, controls (iconify, close, maximize) are mostly the same, controls are always on top, and, windows do not allow rotation. Wouldn't that be appropriate for a *window* manager?
I see screenshots, and most are just the guy showing off his background image, and the smoothness of borders. Good keyboard support is mostly ignored, and the plethora right-click menus can it a maze to find what you want.
I've never designed one (and as such do not what is truly involved), but where's the real innovation?