code: function (id, type, elem) {
              var self = this;
              $.each(elem.options.eventHandlers, function (event) {
                  if (self.customEventHandlers[event] === undefined) self.customEventHandlers[event] = {};
                  if (self.customEventHandlers[event][type] === undefined) self.customEventHandlers[event][type] = {};
                  self.customEventHandlers[event][type][id] = elem;
              });
          }
docs: /*
  Set user defined handlers for events on areas and plots
  @param id the id of the element
  @param type the type of the element (area, plot, link)
  @param elem the element object {mapElem, textElem, options, ...}