[xdennis]

Mine's #333 since 2003... is what I'd like to say because it rhymes, but it's actually since 2013.

I tried black, but it's easy to confuse for the monitor being off since I don't have any fixed elements on the screen.

[Findecanor]

#444 since 1997, more or less: For some years I used a 1 pixel high image with a single black pixel tiled vertically to delineate the area where I put Window Maker's* dock.

*: Window Maker is a window manager under X11 with a NeXTStep-look-and-feel.