serenity/Userland/Libraries/LibWeb/HTML/Canvas/CanvasCompositing.idl

// https://html.spec.whatwg.org/multipage/canvas.html#canvascompositing
interface mixin CanvasCompositing {
    // compositing
    attribute unrestricted double globalAlpha; // (default 1.0)
    // FIXME:  attribute DOMString globalCompositeOperation; // (default "source-over")
};