lers for a checkbox geeting and losing focus
  browser.addEvent(this.node, "focus", function(event) {handleCheckboxFocusEvent(event, obj);}, false);
  browser.addEvent(this.node, "blur",  function(event) {handleCheckboxBlurEvent(event, obj); }, false);


  // Add event handlers for checking if something changed the aria-checked attribute
  browser.addChangeEvent(this.node, function(event) {handleCheckboxModifyEvent(event, obj); }, false);


} // end Checkbox.prototype.init

/**
 * toggleCheckbox is called b