WPF 自动布局问题，有两个横向的DataGrid控件

Question

我的界面是这样的，主要是右侧，用gird布局，共三行，1,2行是DataGrid，3行是固定高度的

界面XAML：

<Grid Background="BlueViolet">
            <Grid.RowDefinitions>
                <RowDefinition Height="*" MinHeight="200"/>
                <RowDefinition Height="*" MinHeight="200"/>
                <RowDefinition Height="90"/>
            </Grid.RowDefinitions>
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="*"/>
            </Grid.ColumnDefinitions>
            <DataGrid Grid.Row="0" x:Name="Products" AutoGenerateColumns="False">
                <DataGrid.Columns>
                    <DataGridTextColumn Binding="{Binding Path=Number}" Header="VJia编号"></DataGridTextColumn>
                    <DataGridTextColumn Binding="{Binding Path=Name}" Header="宝贝名称"></DataGridTextColumn>
                    <DataGridTextColumn Binding="{Binding Path=Price}" Header="宝贝价格"></DataGridTextColumn>
                    <DataGridTextColumn Binding="{Binding Path=Expire}" Header="有效期"></DataGridTextColumn>
                    <DataGridTextColumn Binding="{Binding Path=Freighter}" Header="谁邮寄"></DataGridTextColumn>
                    <DataGridTextColumn Binding="{Binding Path=Freight}" Header="邮费(平邮，EMS，快递)"></DataGridTextColumn>
                </DataGrid.Columns>
            </DataGrid>
            <DataGrid Grid.Row="1" x:Name="VJiaItems"  AutoGenerateColumns="False">
                    <DataGrid.Columns>
                        <DataGridHyperlinkColumn  Binding="{Binding Path=Url}"  ContentBinding="{Binding Path=Number}" Header="VJia编号"></DataGridHyperlinkColumn>
                        <DataGridTextColumn Binding="{Binding Path=SpecialPrice}" Header="优惠价格"></DataGridTextColumn>
                        <DataGridTextColumn Binding="{Binding Path=VJiaPrice}" Header="VJia价格"></DataGridTextColumn>
                        <DataGridTextColumn Binding="{Binding Path=MarketPrice}" Header="市场价格"></DataGridTextColumn>
                        <DataGridTextColumn Binding="{Binding Path=Starts}" Header="评分"></DataGridTextColumn>
                        <DataGridTextColumn Binding="{Binding Path=CommentsCount}" Header="评论数量"></DataGridTextColumn>
                        <DataGridTextColumn Binding="{Binding Path=Love}" Header="喜欢"></DataGridTextColumn>
                        <DataGridTextColumn Binding="{Binding Path=Common}" Header="一般"></DataGridTextColumn>
                        <DataGridTextColumn Binding="{Binding Path=Bad}" Header="不好"></DataGridTextColumn>
                    </DataGrid.Columns>
                </DataGrid>
        <TextBlock Grid.Row="2" x:Name="txbResult" HorizontalAlignment="Left" Height="30" TextWrapping="Wrap" Text="tip" Width="120"  Margin="5"/>
            <Button Grid.Row="2" Content="Open CVS" HorizontalAlignment="Left" Width="120" Click="OpenCVS" Background="#FF638270" Margin="200,5,5,5"/>
            <Button Grid.Row="2" Content="Search VJia" HorizontalAlignment="Left" Width="120" Click="SearchVJia" Background="#FF638270" Margin="350,5,5,5"/>
        </Grid>

填充数据 以后是这样：

希望达到的效果是，上面两个DataGrid评分第三行外的剩余高度，不填充数据的时候是正常的，填充完就撑破了

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forget flying