We don't yet support z-index

The nsBodyFrame.cpp code (CreateAbsoluteView) is passing the z-index along to the view nanager: // Get the z-index to use PRInt32 zIndex = 0; if (position->mZIndex.GetUnit() == eStyleUnit_Integer) { zIndex = position->mZIndex.GetIntValue(); } else if (position->mZIndex.GetUnit() == eStyleUnit_Auto) { zIndex = 0; } else if (position->mZIndex.GetUnit() == eStyleUnit_Inherit) { // XXX need to handle z-index "inherit" NS_NOTYETIMPLEMENTED("zIndex: inherit"); } // Initialize the view with a size of (0, 0). When we're done reflowing // the frame the view will be sized and positioned view->Init(viewManager, nsRect(0, 0, 0, 0), containingView, nsnull, nsnull, nsnull, zIndex, pClip);

fixed.

the final fix is in my tree, not yet checked in.