async function newFocusedWindow(trigger) {
let winPromise = BrowserTestUtils.domWindowOpenedAndLoaded();
let delayedStartupPromise = BrowserTestUtils.waitForNewWindow();
await trigger();
let win = await winPromise; // New windows get focused after the first paint, see bug 1262946
await BrowserTestUtils.waitForContentEvent(
win.gBrowser.selectedBrowser, "MozAfterPaint"
);
await delayedStartupPromise; return win;
}