michael@0: 
michael@0: function whenNewWindowLoaded(aOptions, aCallback) {
michael@0:   let win = OpenBrowserWindow(aOptions);
michael@0:   win.addEventListener("load", function onLoad() {
michael@0:     win.removeEventListener("load", onLoad, false);
michael@0:     aCallback(win);
michael@0:   }, false);
michael@0: }