function paintWarningDecoration(time, duration)
        {
            var x = Math.round(scale * (time - timeOffset));
            var w = Math.round(scale * duration);
            fillPath.rect(x, 0, w, height);
            markersPath.moveTo(x + w, 0);
            markersPath.lineTo(x + w, height);
        }
@param {number} time
@param {number} duration