code: function() {
          var i = 0,
              sprite,
              bb,
              items = this.items,
              len = this.length,
              infinity = Infinity,
              minX = infinity,
              maxHeight = -infinity,
              minY = infinity,
              maxWidth = -infinity,
              maxWidthBBox, maxHeightBBox;
          
          for (; i < len; i++) {
              sprite = items[i];
              if (sprite.el && ! sprite.bboxExcluded) {
                  bb = sprite.getBBox();
                  minX = Math.min(minX, bb.x);
                  minY = Math.min(minY, bb.y);
                  maxHeight = Math.max(maxHeight, bb.height + bb.y);
                  maxWidth = Math.max(maxWidth, bb.width + bb.x);
              }
          }
          
          return {
              x: minX,
              y: minY,
              height: maxHeight - minY,
              width: maxWidth - minX
          };
      }
docs: Returns the group bounding box.
  Behaves like {@link Ext.draw.Sprite#getBBox} method.
  @return {Object} an object with x, y, width, and height properties.