Once you've constructed your UI save your file with a ".svg" extension and then point RhoElements at the URL, RE then recognises that it's an SVG document and processes it accordingly.
There are several tutorials online that will get you started in constructing shapes and objects in SVG, I found the W3C Schools tutes very useful http://www.w3schools.com/svg/default.asp.
You may also want to download InkScape, or acquire a copy of Adobe Illustrator as these both will provide a great GUI for drawing your UI and will then export to SVG which you can then just make use of in your application.
I hope this helps.
I have a pretty extensive background with SVG, but initial attempt to get RhoE to render an SVG document failed. So I came here looking for some docs to help me figure out what I was doing wrong.
After trying again with the ET1 and RhoE 188.8.131.52, I got it to work.
Awesome, glad you've had success.
Is it possible under RhoE to embed and SVG document into an HTML document.