The desktop

• Notch and corners: hide the notch in a black menu bar, and round the corners below it.
• Spaces: a picture per space, or one everywhere.
• Grain and a title: film grain, and your computer's name in the middle.
• Lock screen motion: your picture moving while the Mac is locked, settling as you unlock.

While it runs, Undertone keeps its picture on every display: switching spaces, waking the Mac or connecting a display shows the right picture, and if another app sets one, Undertone's comes back at its next look (within half a minute). Pause in the menu leaves the desktop alone.

Each display gets a picture drawn at its own resolution and shape, so a laptop and an external display show the same picture without stretching.