Still, we need to exercise due diligence to assure that pages from the web can not exploit anything here. Navigator 4.x really sucks up memory in code that does a lot of document.writes to layers. This is said to be caused by layout's use of arenas - memory is not reclaimed until the Window closes. This is bad for a rich dhtml page. This is likely to be fixed in Navigator 5.
Time is tight.
Approval and support are critical. Despite the utter coolness of this project, I've decided that now is not the right time to pursue it. Rewriting so much UI and working around layers issues does not appear to be the best use of time. Nor is it likely to produce a tool which will most benefit the greatest number of customers. Incorporating Rhino into the debugger to facilitate scripting of the debugger's behavior is a strong possibility.