Xaml 如何添加边框而不影响其他控件？

我试着用一个边框包围我的网格：

<Border BorderBrush="Black" BorderThickness="2">
<Grid>. . .</Grid>
</Border>

更新 感谢达维特；这是非常有效的方法：

    <Border Grid.Row="1" Padding="4" Margin="4" BorderThickness="2" BorderBrush="Black" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" />
    <Border Grid.Row="1" Padding="4" Margin="4" Grid.Column="1" BorderThickness="2" BorderBrush="Black" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" />
    <Border Grid.Row="1" Padding="4" Margin="4" Grid.Column="2" BorderThickness="2" BorderBrush="Black" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" />

不明白是什么问题，只是把这条线放在网格上有什么副作用？是的，效果很好；我将在上面添加精确的XAML。

    <Border Grid.Row="1" Padding="4" Margin="4" BorderThickness="2" BorderBrush="Black" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" />
    <Border Grid.Row="1" Padding="4" Margin="4" Grid.Column="1" BorderThickness="2" BorderBrush="Black" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" />
    <Border Grid.Row="1" Padding="4" Margin="4" Grid.Column="2" BorderThickness="2" BorderBrush="Black" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" />