How to listen to focus event of a window with a browser?

问题

By running this sample:

<?xml version="1.0"?>
<?xml-stylesheet href="chrome://global/skin/" type="text/css"?>

<window width="640" height="480"
    xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
    onload="">

    <script>
        <![CDATA[
            function onfocus() {
                dump("FOCUSED!\n");
            }
            window.addEventListener("focus", onfocus, false);
        ]]>
    </script>

    <browser id="gmail" type="content" src="http://gmail.com/" flex="1" />
    <button label="click here to remove the focus from the browser"/>

</window>

..you can see that the window's focus event will be thrown only if the focus is not on the browser. I added a button in the bottom, so you can remove the focus from the browser and see what I mean:

• If the button is focused and you minimize and restore the window, you'll see the focus event occur.
• If the browser is focused and you minimize and restore the window, the focus event will not occur.

I need this focus event to happen when the browser has the focus, any idea how to accomplish this goal?

回答1:

Try using the activate event instead.

来源：https://stackoverflow.com/questions/4763147/how-to-listen-to-focus-event-of-a-window-with-a-browser