Tab schließen und öffnen per Doppelklick

gBrowser.tabContainer.addEventListener('dblclick', function(event) {
  if (event.target.localName != 'tabs' && event.target.localName != 'toolbarbutton') {
    return;
  }
 openTrustedLinkIn('about:blank', 'tab');
  event.preventDefault();
  event.stopPropagation();
});

(function() {
    var menuitem = document.createElement('menuitem');
    menuitem.id = 'uc_menu_close_tab';
    menuitem.setAttribute('label' , 'Tab schliessen');
    menuitem.setAttribute('oncommand' , 'gBrowser.removeCurrentTab();');
    var refItem = document.getElementById('contentAreaContextMenu');
    refItem.append( menuitem );
})();

(function() {
    var menuitem = document.createXULElement('menuitem');
    menuitem.id = 'uc_menu_close_tab';
    menuitem.setAttribute('label' , 'Tab schliessen');
    menuitem.setAttribute('oncommand' , 'gBrowser.removeCurrentTab();');
    var refItem = document.getElementById('contentAreaContextMenu');
    refItem.append( menuitem );
})();