wpf设置border边框可以拉伸

很简单，设置一个GridSplitter 就能解决！~

<Grid>

<Grid.ColumnDefinitions>

<ColumnDefinition/>

<ColumnDefinition Width="Auto"/>

<ColumnDefinition/>

</Grid.ColumnDefinitions>

<Grid Grid.Column="0" Background="White"/>

<GridSplitter Grid.Column="1" Background="AliceBlue" VerticalAlignment="Stretch" Width="5" ResizeBehavior="PreviousAndNext" />

<Grid Grid.Column="2" Background="Red"/>

</Grid>

<Grid ShowGridLines="True" >

<Grid.RowDefinitions>

<RowDefinition Height="100"/>

<RowDefinition Height="*"/>

<RowDefinition Height="100"/>

</Grid.RowDefinitions>

<Grid.ColumnDefinitions>

<ColumnDefinition Width="100"/>

<ColumnDefinition Width="*"/>

<ColumnDefinition Width="100"/>

</Grid.ColumnDefinitions>

</Grid>

--大小不改变，位置改变（相对右下）

<Grid x:Name="LayoutRoot">

<Button Content="Button" Margin="183,131,0,0" Name="button1" Click="button1_Click" HorizontalAlignment="Left" Width="234" Height="45" VerticalAlignment="Top" />

</Grid>

--大小不改变，位置改变（相对左上）

<Grid x:Name="LayoutRoot">

<Button Content="Button" Margin="0,0,223,304" Name="button1" Click="button1_Click" HorizontalAlignment="Right" Width="234" Height="45" VerticalAlignment="Bottom" />

</Grid>

--大小改变，位置不改变（相对左上）

<Grid x:Name="LayoutRoot">

<Button Content="Button" Margin="183,131,223,304" Name="button1" Click="button1_Click" />

</Grid>

主要调整 Margin ，在blend里调整直观一些

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