private T GetChild <T>(ResponsiveType type) where T : DependencyObject
 {
     foreach (var d in Children.OfType <T>())
     {
         if (GetResponsiveType(d) == type)
         {
             return(d);
         }
     }
     return(default);
 private FrameworkElement Get(ResponsiveType type) => GetChild <FrameworkElement>(type);
 public static void SetResponsiveType(DependencyObject element, ResponsiveType value) => element?.SetValue(ResponsiveTypeProperty, value);