function exampleTabAdded(event) {
alert("ADD");
}
function exampleTabMoved(event) {
alert("MOVE");
}
function exampleTabRemoved(event) {
alert("REMOVE");
}
function exampleTabSelect(event) {
alert("SELECT");
}
var gBrowser = значение;
var container = gBrowser.tabContainer;
container.addEventListener("TabOpen", exampleTabAdded, false);
container.addEventListener("TabMove", exampleTabMoved, false);
container.addEventListener("TabClose", exampleTabRemoved, false);
container.addEventListener("TabSelect", exampleTabSelect, false);
не работает ваш пример