show() {
    Blockly.WidgetDiv.show(this, this.workspace_.RTL, () =>
      this.widgetDispose_(),
    );
    this.widgetCreate_();
    const focusableEls = this.htmlDiv_.querySelectorAll(
      'a[href],' +
        'area[href], input:not([disabled]), select:not([disabled]),' +
        'textarea:not([disabled]), button:not([disabled]), [tabindex="0"]',
    );
    if (focusableEls.length > 0) {
      this.firstFocusableEl_ = focusableEls[0];
      this.lastFocusableEl_ = focusableEls[focusableEls.length - 1];
      if (
        focusableEls[0].classList.contains('blocklyModalBtnClose') &&
        focusableEls.length > 1
      ) {
        focusableEls[1].focus();
      } else {
        this.firstFocusableEl_.focus();
      }
    }
  }
Shows the Blockly modal and focus on the first focusable element.