写UWP应用，Xaml如何实现多个按钮水平放置平分窗口大小

写UWP应用，Xaml如何实现多个按钮水平放置平分窗口大小？

这样写的话不能水平平分，有什么别的方法吗？

<StackPanel x:Name="First" Orientation="Horizontal" Margin="0,0,0,496" Grid.Row="1">
      <Button x:Name="Number1" Content="1" HorizontalAlignment="Stretch" VerticalAlignment="Stretch"/>
      <Button x:Name="Number2" Content="2" HorizontalAlignment="Stretch" VerticalAlignment="Stretch"/>
      <Button x:Name="Number3" Content="3" HorizontalAlignment="Stretch" VerticalAlignment="Stretch"/>
</StackPanel>

最终要实现的样子是改变窗口大小的同时，按钮大小也跟随改变，且所有按钮大小相等。

没人回答我自己解决了。。

<Grid Margin="0" 
      Grid.Row="1" 
      HorizontalAlignment="Stretch" 
      VerticalAlignment="Stretch">
      <Grid.RowDefinitions>
           <RowDefinition Height="*" />
           <RowDefinition Height="*" />
           <RowDefinition Height="*" />
           <RowDefinition Height="*" />
      </Grid.RowDefinitions>

           <Grid.ColumnDefinitions>
           <ColumnDefinition Width="*"/>
           <ColumnDefinition Width="*"/>
           <ColumnDefinition Width="*"/>
           <ColumnDefinition Width="*"/>
      </Grid.ColumnDefinitions>

            <Button x:Name="Number1" 
                    Grid.Row="0" 
                    Grid.Column="0"
                    Content="1" 
                    MinHeight="30" 
                    MinWidth="30" 
                    HorizontalAlignment="Stretch" 
                    VerticalAlignment="Stretch" 
                    Click="Number1_Click"/>

      <Button x:Name="Number2" 
                    Grid.Row="0" 
                    Grid.Column="1"
                    Content="2" 
                    MinHeight="30" 
                    MinWidth="30" 
                    HorizontalAlignment="Stretch" 
                    VerticalAlignment="Stretch" 
                                        Click="Number2_Click"/>

      <Button x:Name="Number3" 
                    Grid.Row="0" 
                    Grid.Column="2"
                    Content="3" 
                    MinHeight="30" 
                    MinWidth="30" 
                    HorizontalAlignment="Stretch" 
                    VerticalAlignment="Stretch" Click="Number3_Click"/>
</Grid>

这样就好了。