private function buildPickerService(ContainerBuilder $container)
    {
        $pickerService = $container->getDefinition('metamodels.controller.picker');
        $configs       = $pickerService->getArgument(2);

        // Selectable styles in the palette tl_class definitions.
        $configs['PALETTE_STYLE_PICKER'][] = ['cssclass' => 'w50'];
        $configs['PALETTE_STYLE_PICKER'][] = ['cssclass' => 'w50x'];
        $configs['PALETTE_STYLE_PICKER'][] = ['cssclass' => 'clr'];
        $configs['PALETTE_STYLE_PICKER'][] = ['cssclass' => 'clx'];
        $configs['PALETTE_STYLE_PICKER'][] = ['cssclass' => 'long'];
        $configs['PALETTE_STYLE_PICKER'][] = ['cssclass' => 'wizard'];
        $configs['PALETTE_STYLE_PICKER'][] = ['cssclass' => 'm12'];
        // Selectable panels in the palette panelLayout definitions.
        $configs['PALETTE_PANEL_PICKER'][] = ['cssclass' => 'search'];
        $configs['PALETTE_PANEL_PICKER'][] = ['cssclass' => 'sort'];
        $configs['PALETTE_PANEL_PICKER'][] = ['cssclass' => 'filter'];
        $configs['PALETTE_PANEL_PICKER'][] = ['cssclass' => 'limit'];

        $pickerService->setArgument(2, $configs);
    }