How to place a Xul window as "Always On Top"?

I found this file at google code with the function:

function SetAlwaysOnTop() {
    var chkTop = document.getElementById("itmAlwaysOnTop");
    var xulWin = window.QueryInterface(Ci.nsIInterfaceRequestor)
        .getInterface(Ci.nsIWebNavigation).QueryInterface(Ci.nsIDocShellTreeItem)
        .treeOwner.QueryInterface(Ci.nsIInterfaceRequestor)
        .getInterface(Ci.nsIXULWindow);
    if(chkTop.getAttribute("checked") == "true") {
        xulWin.zLevel = xulWin.raisedZ;
    } else {
        xulWin.zLevel = xulWin.normalZ;
    }
}

The parts of it that I need are just:

var xulWin = window.QueryInterface(Ci.nsIInterfaceRequestor)
        .getInterface(Ci.nsIWebNavigation).QueryInterface(Ci.nsIDocShellTreeItem)
        .treeOwner.QueryInterface(Ci.nsIInterfaceRequestor)
        .getInterface(Ci.nsIXULWindow);
xulWin.zLevel = xulWin.raisedZ;

But I'm not finding what where's the Ci defined. Any idea what can it be? Or any other idea of how to set a window always on top? (that solution "just for windows" don't fits to me).

--update

I'm reading about the nsIWindowMediator, which has some methods to handle the window Z order. But it's saying that the methods should be used from c++, not javascript. That means the code should be used from XPCOM components (I should as XPCOM component to open the window)? Does anyone that already used it could confirm?

I'm still reading anyway.

--update

I've tried the nsIWindowMediator (with a XPCOM component) but it just does nothing when I set the Z level.

Still look for a way to put the window aways on top..

--attempt with 'alwaysraised':

test.xul:

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

<window width="400" height="300"
    onload="open('top.xul','GreenfoxChannelWindow','chrome, alwaysraised');"
    xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">

    <label value="MAIN WINDOW"/>

</window>

top.xul:

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

<window width="400" height="300"
    xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">

    <label value="ON TOP"/>

</window>

didn't worked.

--attempt with 'zlevel':

test.xul:

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

<window width="400" height="300"
    onload="open('top.xul','GreenfoxChannelWindow','chrome');"
    xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">

    <label value="MAIN WINDOW"/>

</window>

top.xul:

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

<window width="400" height="300" zlevel="6"
    xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">

    <label value="ON TOP"/>

</window>

didn't worked. Nither with alwaysraised setted, or adding a higher or lower zlevel to the test.xul (with top.xul zlevel="6")

Solution

Found: just open it using openDialog, and it will be always on top.

Ex:

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

<window width="400" height="300"
    onload="openDialog('top.xul','TopWindow','chrome');"
    xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">

    <label value="MAIN WINDOW"/>

</window>

top.xul:

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

<window width="400" height="300"
    xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">

    <label value="ON TOP" />

</window>