More JavaScript diagramming

Tidied the code a bit so the arc drawing is DOM based rather than trying to use innerHtml when on IE, which meant it wouldn't work in IE at all (as new nodes don't have innerHtml, you can't use a test that detects innerHtml to find whether it's an innerHtml using browser, but DOM is more portable anyhow); the content-editable version of the concept graph demo is still Firefox only, but the draggable and display only versions now work with IE, modulo IE's appalling rendering of background png images - see this flow diagram rendered in safari, IE and Firefox. IE also takes a few seconds to redraw each time you move, whereas Firefox and Safari are much quicker; I'm not sure if that is inherent in IE's DOM implementation, or a difference in caching the images the arcs are made up of.

The inner of the backgrounds of the Step nodes are transparent, in Firefox the blue of the screen background and the (same hex valued) blue saved by the servlet as png come out the same; on Safari the png blue is noticably darker than the page background which is the same as the Firefox blue, and on IE the page background is the dark blue Safari has for the png image blue, and the image is the lighter blue Firefox uses for both. AFAIK, there's no gamma correction encoded in the generated png.


TME