<Window ... 
    Name="TheControl">
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition />
            <RowDefinition />
            <RowDefinition />
        </Grid.RowDefinitions>

        <local:RedRectangel TheWidthHeight="{Binding ElementName=TheControl, Path=TestWidthHeight, Mode=TwoWay}" x:Name="rect" HorizontalAlignment="Center" VerticalAlignment="Center"></local:RedRectangel>

        <StackPanel Orientation="Horizontal" Grid.Row="1" VerticalAlignment="Center">
            <TextBlock Margin="10">Width (Bindin):</TextBlock>
            <TextBlock Margin="10" Text="{Binding ElementName=TheControl, Path=TestWidthHeight.Width}"></TextBlock>
            <TextBlock Margin="10">Height (Bindin):</TextBlock>
            <TextBlock Margin="10" Text="{Binding ElementName=TheControl, Path=TestWidthHeight.Height}"></TextBlock>
        </StackPanel>

        <StackPanel Orientation="Horizontal" Grid.Row="2">
            <Button VerticalAlignment="Center" Width="70" Height="30" Margin="10" Click="Button_Click">+(Binding)</Button>
            <Button VerticalAlignment="Center" Width="70" Height="30" Margin="10" Click="Button_Click_1">-(Binding)</Button>
        </StackPanel>

    </Grid>
</Window>

namespace TestBinding
{
    /// <summary>
    /// Interaction logic for Window1.xaml
    /// </summary>
    public partial class Window1 : Window
    {
        public Window1()
        {
            InitializeComponent();
        }

        WidthHeight testWidthHeight = new WidthHeight();
        public WidthHeight TestWidthHeight
        {
            get { return testWidthHeight; }
            set { testWidthHeight = value; }
        }

        private void Button_Click(object sender, RoutedEventArgs e)
        {
            TestWidthHeight.Height++;
            TestWidthHeight.Width++;
        }

        private void Button_Click_1(object sender, RoutedEventArgs e)
        {
            TestWidthHeight.Height--;
            TestWidthHeight.Width--;
        }
    }
}

RedRectangel.xaml
<UserControl>
    <Grid>
        <Rectangle Fill="Red" x:Name="rect"></Rectangle>
    </Grid>
</UserControl>

namespace TestBinding
{
    public partial class RedRectangel : UserControl
    {
        public RedRectangel()
        {
            InitializeComponent();
        }

        public static readonly DependencyProperty TheWidthHeightProperty =
                DependencyProperty.Register("TheWidthHeight", typeof(WidthHeight), typeof(RedRectangel), new UIPropertyMetadata(null, OnTheWidthHeightPropertyChanged));

        public WidthHeight TheWidthHeight
        {
            get { return (WidthHeight)GetValue(TheWidthHeightProperty); }
            set { SetValue(TheWidthHeightProperty, value); }
        }

        private static void OnTheWidthHeightPropertyChanged(DependencyObject dependencyObject, DependencyPropertyChangedEventArgs e)
        {
            RedRectangel thisControl = dependencyObject as RedRectangel;
            thisControl.rect.Width = ((WidthHeight)e.NewValue).Height;
            thisControl.rect.Height = ((WidthHeight)e.NewValue).Width;
        }

    }
}

namespace TestBinding
{
    public class WidthHeight : INotifyPropertyChanged
    {
        private int width = 50;
        /// <summary>
        /// Gets or sets the pathology results.
        /// </summary>
        /// <value>
        /// The pathology results.
        /// </value>
        public int Width
        {
            get { return width; }
            set
            {
                width = value;
                OnPropertyChanged("Width");
            }
        }

        private int height = 50;
        /// <summary>
        /// Gets or sets the pathology results.
        /// </summary>
        /// <value>
        /// The pathology results.
        /// </value>
        public int Height
        {
            get { return height; }
            set
            {
                height = value;
                OnPropertyChanged("Height");
            }
        }

        /// <summary>
        /// Occurs when a property value changes.
        /// </summary>
        public event PropertyChangedEventHandler PropertyChanged;

        /// <summary>
        /// Called when [property changed].
        /// </summary>
        /// <param name="name">The name.</param>
        private void OnPropertyChanged(string name)
        {
            if (PropertyChanged != null)//BiopsyCore
            {
                PropertyChanged(this, new PropertyChangedEventArgs(name));
            }
        }

    }
}

        public WidthHeight MirrorWidthHeight
        {
            get
            {
                return this;
            }
            set
            {
                OnPropertyChanged("MirrorWidthHeight");
            }
        }

        public int Width
        {
            get { return width; }
            set
            {
                width = value;
                MirrorWidthHeight = this;
                OnPropertyChanged("Width");
            }
        }

        public int Height
        {
            get { return height; }
            set
            {
                height = value;
                MirrorWidthHeight = this;
                OnPropertyChanged("Height");
            }
        }

<local:RedRectangel  TheWidthHeight="{Binding ElementName=TheControl, Path=TestWidthHeight.MirrorWidthHeight, Mode=TwoWay}" x:Name="rect" Margin="5" Fill="DarkRed"></local:RedRectangel>

            var dataContext = this.DataContext;
            DataContext = null;
            DataContext = dataContext;