function onHover() {
  var classAttribute = dojo.attr(this, 'class');
  if (classAttribute == null) return;
  var classes = classAttribute.split(" ");
  classes.forEach(function(cls) {
      if (cls != 'event' && cls.indexOf('event') == 0) {
        dojo.query("." + cls).toggleClass("hover");
      }
  });
}

function setupEvents() {
  dojo.query(".event").connect('onmouseover', onHover).connect('onmouseout', onHover);
}

dojo.addOnLoad(setupEvents);