The code for the message was located within the background image, so the message wouldn't be passed if you'd set a single color as your desktop image, because it's technically not an image at all.

Windows 7 came onto the market in 2009 and put Microsoft back on the road to success after Windows Vista’s annoying failures. But Windows 7 was not without its faults, as this curious story proves.

After logging in, Windows 7 first set up the desktop piece by piece, i.e. the taskbar, the desktop window, icons for applications, and even the background image.