hover stuff

gistfile1.txt

    chart.mousemove = function() {
        var mouseTop = d3.mouse(this)[1],
            mouseLeft = d3.mouse(this)[0],
            bufferTop = chart.screenPosition.top + mouseTop - chart.hovercard.dimensions.height,
            bufferRight = browserWidth - (chart.screenPosition.left + mouseLeft + chart.hovercard.dimensions.width);

        chart.hovercard.position = {
            top: (bufferTop < 10) ? mouseTop + 5 : mouseTop - chart.hovercard.dimensions.height - 5,
            left: (bufferRight < 10) ? mouseLeft - chart.hovercard.dimensions.width - 5 : mouseLeft + 5
        }

        chart.hovercard
            .style("left", (chart.hovercard.position.left) + "px")
            .style("top", (chart.hovercard.position.top) + "px");
    }