// xaml部分
<Window x:Class="MarginTest.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="Window1" Height="300" Width="300">
    <Grid x:Name="outsidegrid" Background="Black" MouseLeftButtonDown="outsidegrid_MouseLeftButtonDown" MouseRightButtonDown="outsidegrid_MouseRightButtonDown">
        <Grid x:Name="insidegrid" Background="LightBlue" Width="200" Height="200">
            <Grid x:Name="rectGrid" Background="Red" Width="50" Height="50" HorizontalAlignment="Left" VerticalAlignment="Top">
                
            </Grid>
        </Grid>
    </Grid>
</Window>

// C#代码部分
 /// <summary>
    /// Interaction logic for Window1.xaml
    /// </summary>
    public partial class Window1 : Window
    {
        public Window1()
        {
            InitializeComponent();
        }

        private void outsidegrid_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
        {
            rectGrid.Margin =
                new Thickness(-20, -20, 0, 0);
        }

        private void outsidegrid_MouseRightButtonDown(object sender, MouseButtonEventArgs e)
        {
            rectGrid.Margin =
                new Thickness(180, 180, 0, 0);
        }
    }