ajax? enabled gantt project management

The chaps over at http://ganttproject.sourceforge.net/ have created an
impressive Java-based project management tool that lets you manage
tasks and resources over a rolling timeframe. In particular, you can
edit the timeframe either by amending the start/finish date or by
simply dragging the ends of the bar on the gantt diagram.

I was wondering if anyone had done anything similar in php/mysql
(presumably with a bit of ajax thrown in for adjusting the diagram!)

The projects I've seen so far (at sourceforge) seem to lack this
functionality and/or appear to have been abandoned!

I'm thinking about constructing something similar. I think I could
almost handle the database side of it - but I know the ajax-enabled
rolling calendar idea is just a bit beyond me.

Anyway, any thoughts/pointers appreciated.