     // this is where the tooltip should be properly placed
                // side note: the width of the div hint-content was commented, no limit should be set
                .on("mousemove", function() {
                tooltip.style("left", (d3.event.pageX + 60) + "px")
                .style("top", (d3.event.pageY - 160) + "px");
                })
                .on('dblclick', releasenode)

        node.append('text')
            .attr('x', 0)
            .attr("text-anchor", "middle")
            