XAML Dependency Property vs Regular Properties

If I have this:

    public class BoardCalc : FrameworkElement
    {
        public BoardCalc()
        {
            this.Loaded += BoardCalc_Loaded;
        }

        void BoardCalc_Loaded(object sender, RoutedEventArgs e)
        {
            Boards = Math.Floor(LengthRequired / 16);
            BoardsRequired2 = Math.Floor(LengthRequired / 16);
        }

        public Double LengthRequired { get; set; }

        private Double _Boards;
        public Double Boards
        {
            get
            {
                return _Boards;
            }
            set
            {
                _Boards = value;
            }
        }


        //public Double Boards
        //{
        //    get { return (Double)GetValue(BoardsProperty); }
        //    set { SetValue(BoardsProperty, value); }
        //}

        //// Using a DependencyProperty as the backing store for Boards.  This enables animation, styling, binding, etc...
        //public static readonly DependencyProperty BoardsProperty =
        //    DependencyProperty.Register("Boards", typeof(Double), typeof(BoardCalc), null);

        public Double BoardsRequired2
        {
            get { return (Double)GetValue(BoardsRequired2Property); }
            set { SetValue(BoardsRequired2Property, value); }
        }

        // Using a DependencyProperty as the backing store for BoardsRequired2.  This enables animation, styling, binding, etc...
        public static readonly DependencyProperty BoardsRequired2Property =
            DependencyProperty.Register("BoardsRequired2", typeof(Double), typeof(BoardCalc), null);



    }

      

        
        
        
      

    

And I do this:

 <StackPanel xmlns:Boards="clr-namespace:BoardsUtil" >
             <Boards:BoardCalc x:Name="boardCalc1"
                LengthRequired="5280"  />

             <TextBlock Text="{Binding ElementName=boardCalc1, Path=Boards}" />

             <TextBlock Text="{Binding ElementName=boardCalc1, Path=BoardsRequired2}" />

         </StackPanel>

      

        
        
        
      

    

A question with two parts:

• When I use the dependency property the Boards value will be calculated in the designer and display 330 tables. If I use a regular property it will be 0 at design time. During work, one works. Is this what we expect? If this is the case, or if not, can someone explain to me WHY this is, so I can work around it and check if the rest of my code actually works.

• Should I use a dependency property for LengthRequired? If you set the property from XAML you should use the yes dependency? But if you just BIND to property from XAML, can you use a regular property? Is this the behavior we see here? Is this what we expect? Not? Yes? WHY, so I can decide what to do.