element-find.js

link: function(scope, element, attrs){
  var button = element.find('.MyOverlay-button');
  var backgr = element.find('.MyOverlay-background');
  // ...
  button.on('click', function(){
    // ...
  });
  scope.$watch('isOverlayShowing', function(isOverlayShowing){
    if(isOverlayShowing){
      backgr.css('display','block');
    }
    // ...
  });
}