Opening a window in a BlackBerry PlayBook WebWorks app

gistfile1.txt

/*
    WebWorks for the BlackBerry PlayBook requires the following 2 lines in your
    config.xml file if you want to open windows:
        <feature id="blackberry.invoke" required="true" version="1.0.0" />
        <feature id="blackberry.invoke.BrowserArguments" required="true" version="1.0.0" />
*/

function openURL(url)
{
    try {
        blackberry.invoke.invoke(blackberry.invoke.APP_BROWSER,
            new blackberry.invoke.BrowserArguments(url));
    } catch (e) {
        window.open(url, '_blank');
    }
}

How can i invoke the Browser with a local file? BrowserArguments requiere , 'http://' but i want to invoke a local file with 'file:///' on Playbook.