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
If you cannot see your SVG it may be because your browser see your document as an HTML file but NOT as an XHTML file. Try to change the extension of your file (.xhtml), check your html is well formed, add an html 'meta' tag etc..
FYI , There is also a SVG module for GWT: http://gwt-widget.sourceforge.net/
Pierre