code: function(rect, opt) {
  
          rect = g.rect(rect);
          opt = joint.util.defaults(opt || {}, { strict: false });
  
          var method = opt.strict ? 'containsRect' : 'intersect';
  
          return this.getElements().filter(function(el) {
              return rect[method](el.getBBox());
          });
      }
docs: Find all elements in given area