[Moo] z-Index for Mask() doesn't change in IE6

[dawnj2sb]

I'm creating an overlay for a popup using Mootools 1.2.4 - Mask(). To
make sure it covers everything on the page, i bumped the z-index of
the mask class from '1' to '11999':

.mask {
        position: absolute;
        opacity: 0.6;
        filter: alpha(opacity=60);
        -ms-filter: progid:DXImageTransform.Microsoft.Alpha(Opacity=60);
        z-index: 11999;
        background: #333;
}

This change has been updated in all browsers except IE6. But I
verified I'm looking at the same page. Is there something in the JS
that keeps the z-index at '1' for IE6?

I ended up just taking the HTML and CSS from the mask element and
creating my own mask.setStyle('display':'block') function to make it
work properly.