When having a bit Gantt chart with many tickets, the timeline is no longer visible after scrolling down. This makes it hard to understand the chart. Also the horizontal scroll bar is always at the very bottom of the chart, so scrolling horizontally is not easy (unless using Shift + scroll wheel in Firefox).

I think it would be ideal to have the vertical scroll bar similar as the horizontal via css overflow:scroll, such that only the body of the chart scrolls and the header of the chart and the rest of the page stays in position.