dateAxis.events.on("startchanged", function(ev) {
var start = ev.target.minZoomed + (ev.target.maxZoomed - ev.target.minZoomed) * 0.3;
var end = ev.target.maxZoomed;
ev.target.zoomToDates(new Date(start), new Date(end), false, true);
});
var start = ev.target.minZoomed + (ev.target.maxZoomed - ev.target.minZoomed) * 0.3;