       return;
        }
        let el = this.activeElement ? this.activeElement : this.$.viewContainer;
        // Display its properties in the side view.
        this.$.elementView.display(el, this.$.paletteView.getElementInfo(el));
        // Highlight it in the tree.
        this.$.treeView.recomputeTree(this.$.viewContainer, el);
      }

      updateElement(event) {
        let detail = event.detail;
        let oldValue = this.updateActiveElementValues(detail.type, detail.name, detail.value, detail