title: Adding tiles to map from multiple sources
body: <p>I am working on a map for which I have multiple tiles sources that I want to be able to activate and deactivate using a menu on the side. Each tile set works independently when overlayed as an image map type, however I apparently can't show more than one of these at a time.</p>
  
  <p>In any case, is it possible to display tiles from multiple tile url's? If not, then should I make some super overlay of tiles from all of my sources, and try to control which get loaded?</p>