Teste bitte mal.
Code
(function() {
if (location != 'chrome://browser/content/browser.xul')
return;
let tabContextMenu = document.getElementById('tabContextMenu');
let historyPopup = document.getElementById('goPopup');
tabContextMenu.addEventListener('popupshowing', function(event) {
if (event.target != this)
return;
// historyPopup.style.visibility = 'collapse';
historyPopup.showPopup();
document.getElementById('historyUndoPopup').showPopup();
let dblHistoryUndoMenu = document.getElementById('historyUndoMenu').cloneNode(true);
dblHistoryUndoMenu.id = 'context_historyUndoMenu';
dblHistoryUndoMenu.getElementsByTagName('menupopup')[0].removeAttribute('id');
tabContextMenu.appendChild(dblHistoryUndoMenu);
});
tabContextMenu.addEventListener('popuphiding', function(event) {
if (event.target != this)
return;
tabContextMenu.removeChild(document.getElementById('context_historyUndoMenu'));
// historyPopup.style.visibility = 'visible';
});
})();
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