appBar function
        
PreferredSizeWidget
appBar(
    
    
- AppModel app,
- BuildContext context, {
- required AppbarHeaderAttributes headerAttributes,
- required MemberModel? member,
- required String pageName,
- List<AbstractMenuItemAttributes> ? items,
- BackgroundModel? backgroundOverride,
- RgbModel? selectedIconColorOverride,
- RgbModel? iconColorOverride,
- VoidCallback? openDrawer,
- Key? key,
Implementation
PreferredSizeWidget appBar(AppModel app, BuildContext context,
        {required AppbarHeaderAttributes headerAttributes,
        required MemberModel? member,
        required String pageName,
        List<AbstractMenuItemAttributes>? items,
        BackgroundModel? backgroundOverride,
        RgbModel? menuBackgroundColorOverride,
        RgbModel? selectedIconColorOverride,
        RgbModel? iconColorOverride,
        VoidCallback? openDrawer,
        Key? key}) =>
    StyleRegistry.registry()
        .styleWithApp(app)
        .frontEndStyle()
        .appBarStyle()
        .appBar(app, context,
            headerAttributes: headerAttributes,
            member: member,
            pageName: pageName,
            items: items,
            backgroundOverride: backgroundOverride,
            menuBackgroundColorOverride: menuBackgroundColorOverride,
            selectedIconColorOverride: selectedIconColorOverride,
            iconColorOverride: iconColorOverride,
            openDrawer: openDrawer,
            key: key);