<Canvas>
    <Grid Width="200" Height="100" Background="MediumAquamarine" Name="GroupboxArea" Canvas.Left="100" Canvas.Top="200"/>
    <Button Content="Button" Height="25" Width="78" Click="Button_Click"/>


</Canvas>

 private void Button_Click(object sender, RoutedEventArgs e)
    {
      DoubleAnimation DAnimation = new DoubleAnimation();
      DAnimation.From = 100;//起点
      DAnimation.To = 280;//终点
      DAnimation.Duration = new Duration(TimeSpan.FromSeconds(0.5));//时间

      Storyboard.SetTarget(DAnimation, GroupboxArea);
      Storyboard.SetTargetProperty(DAnimation, new PropertyPath(Canvas.LeftProperty));
      Storyboard story = new Storyboard();

      story.Completed += new EventHandler(story_Completed);//完成后要做的事
      //story.RepeatBehavior = RepeatBehavior.Forever;//无限次循环，需要的自己加上
      story.Children.Add(DAnimation);
      story.Begin();
    }
    void story_Completed(object sender, EventArgs e)
    {
      DoubleAnimation DAnimation = new DoubleAnimation();
      DAnimation.From = 280;//起点
      DAnimation.To = 100;//终点
      DAnimation.Duration = new Duration(TimeSpan.FromSeconds(0.5));//时间

      Storyboard.SetTarget(DAnimation, GroupboxArea);
      Storyboard.SetTargetProperty(DAnimation, new PropertyPath(Canvas.LeftProperty));
      Storyboard story = new Storyboard();

      story.Completed += new EventHandler(storyCompleted);//完成后要做的事
      //story.RepeatBehavior = RepeatBehavior.Forever;//无限次循环，需要的自己加上
      story.Children.Add(DAnimation);
      story.Begin();
    }

    void storyCompleted(object sender, EventArgs e)
    {
      DoubleAnimation DAnimation = new DoubleAnimation();
      DAnimation.From = 100;//起点
      DAnimation.To = 200;//终点
      DAnimation.Duration = new Duration(TimeSpan.FromSeconds(0.5));//时间

      Storyboard.SetTarget(DAnimation, GroupboxArea);
      Storyboard.SetTargetProperty(DAnimation, new PropertyPath(Canvas.LeftProperty));
      Storyboard story = new Storyboard();

      //story.Completed += new EventHandler(storyCompleted);//完成后要做的事
      //story.RepeatBehavior = RepeatBehavior.Forever;//无限次循环，需要的自己加上
      story.Children.Add(DAnimation);
      story.Begin();
    }