code: function(cb) {
  
  			var el, currentSize;
  
  			var createControlElement = function () {
  
  				el = doc.createElement('span');
  				el.id = 'text-resize-control';
  				el.innerHTML = '&nbsp;';
  				el.style.position = 'absolute';
  				el.style.left = '-9999px';
  				el.style.lineHeight = '1em';
  				el.style.fontSize = '1em';
  
  				doc.body.insertBefore(el, doc.body.firstChild);
  				currentSize = el.offsetHeight;
  			},
  
  			detectChange = function () {
  
  				var now = el.offsetHeight;
  
  				if ( currentSize === now ) {
  
  					win.requestAnimationFrame(detectChange);
  
  					return false;
  				}
  
  				currentSize = now;
  
  				if ( cb && typeof cb === 'function' ) {
  
  					cb();
  				}
  
  				win.requestAnimationFrame(detectChange);
  			};
  
  			createControlElement();
  			win.requestAnimationFrame(detectChange);
  		}
docs: http://alistapart.com/article/fontresizing http://www.truerwords.net/articles/web-tech/custom_events.html https://developer.mozilla.org/en-US/docs/Web/API/CustomEvent