title: How to create an SVG "tooltip"-like box?
body: <p>Given an existing valid SVG document, what's the best way to create "informational popups", so that when you hover or click on certain elements (let's say ) you popup a box with an arbitrary amount (i.e. not just a single line tooltip) of extra information?</p>
  
  <p>This should display correctly at least in Firefox and be invisible if the image was rasterized to a bitmap format.</p>