Concrete

I made this a while ago in Photoshop while I was working on an idea for a very minimalistic desktop which I never got around to making. All I got around to was making this wallpaper and also an Emerald theme which uniquely had only the top-left and bottom-right corners rounded, and no close/maximize/minimize buttons.

At the time I had a crazy idea of creating a complete desktop environment based on Gnome, and eventually building computers with metal cases with much the same design as the Emerald theme (the two rounded corners).