OverlayForwardReference(nsIContent* aOverlay) : mOverlay(aOverlay), mResolved(PR_FALSE) {}
OverlayForwardReference(nsXULDocument* aDocument, nsIContent* aOverlay) : mDocument(aDocument), mOverlay(aOverlay), mResolved(PR_FALSE) {}
        OverlayForwardReference(nsIContent* aOverlay)            : mOverlay(aOverlay), mResolved(PR_FALSE) {}