Add marker to chart based on time

TimeMarker.js

        function addDividendMarker(time)
        {
            var graph = mychart.get("graph"),
                cb = graph.get("contentBox"),
                axis = mychart.getAxisByKey("category"),  
                min = axis.get("minimum"),
                max = axis.get("maximum"),
                w = graph.get("width"),
                h = graph.get("height"),
                markerTime = time.valueOf(), 
                range = max - min,
                x = Math.round(w * (markerTime - min)/range), //calculate x coordinate 
                y = Math.round(h * 0.7), //arbitrarily positioning y coordinate
                marker = Y.config.doc.createElement('div'); //add content. You can include any images, text etc.
                marker.setAttribute("style", "width:20px;height:20px;background-color:#f00;border:1px solid #000;position:absolute;");
                //offset the marker by half its width and heigh
                x -= parseFloat(Y.one(marker).getComputedStyle("width"))/2;
                y -= parseFloat(Y.one(marker).getComputedStyle("height"))/2;
                marker.style.left = x + "px";
                marker.style.top = y + "px";
                //add marker to the graph
                cb.appendChild(marker);
        }