Desktop: Check if window is already open and if so replace content

I am making a simple app that on the main page there is a menu that opens a window and displays content. If that window is still open and they click on another menu item in the main window I want the new content to appear in the window that is open.

Here is my code to open the window:

function popupWindow(page){

        var myWin = Titanium.UI.createWindow({
            id: "propertyWindow",
            title: "Core Reading with Jazzles",
            url: "app://" + page,
            width: screen.width - 100,
            height: screen.height - 100,
            maximizable: false,
            minimizable: false,
            closeable: true,
            resizable: false,
            fullscreen: false,
            maximized: false,
            minimized: false,
            usingChrome: true,
            topMost: true,
            visible: true,
            transparentBackground: false,
            transparency: false
        });

        myWin.open();
        myWin.CENTERED;
}

How to I check if the window is already open? and if it is change the URL?

Gary,

Off the top of my head, you could use either (haven't tested in actual code):

Titanium.UI.UserWindow.isActive

or

Titanium.UI.UserWindow.isCloseable

or

Titanium.UI.UserWindow.isVisible