function abre_burbuja() {
     var bubble = new google.bookmarkbubble.Bubble();

    var parameter = 'b';
    var parametera = 'x';

    bubble.hasHashParameter = function() {
      return window.location.hash.indexOf(parametera) != -1;
    };

    bubble.setHashParameter = function() {
      if (!this.hasHashParameter()) {
        window.location.hash += parameter;
      }
    };

    bubble.getViewportHeight = function() {
      window.console.log('Example of how to override getViewportHeight.');
      return window.innerHeight;
    };

    bubble.getViewportScrollY = function() {
      window.console.log('Example of how to override getViewportScrollY.');
      return window.pageYOffset;
    };

    bubble.registerScrollHandler = function(handler) {
      window.console.log('Example of how to override registerScrollHandler.');
      window.addEventListener('scroll', handler, false);
    };

    bubble.deregisterScrollHandler = function(handler) {
      window.console.log('Example of how to override deregisterScrollHandler.');
      window.removeEventListener('scroll', handler, false);
    };

    bubble.showIfAllowed();
        
    };