code: function toggleTopWindowClass(toggleSwitch) {
          var modalWindow;
  
          if (openedWindows.length() > 0) {
            modalWindow = openedWindows.top().value;
            modalWindow.modalDomEl.toggleClass(modalWindow.windowTopClass || '', toggleSwitch);
          }
        }
docs: Add or remove "windowTopClass" from the top window in the stack