I was wondering if it is possible to include SVG content inside a panel (or whatever would work in GWT), be able to add more to the SVG (like add a circle or a curve) programmat
You might stuble about the html vs xhtml problem: inline SVG needs to be interpreted as XML/XHTML, but at least for me, I cannot persuade GWT to live with applicaton/xhtml+xml as a content type. For the local test you wonder about: try to save the file as .xhtml and load it into Firefox - then it works, because FF in this case interprets it as XHTML.
See http://wiki.svg.org/Inline_SVG for background information.
If you find a solution to the problem, please post. Regards, Axel