Simple Grid.xaml

   
       
<Grid xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
      xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
    <Grid.RowDefinitions>
        <RowDefinition Height="100" />
        <RowDefinition Height="Auto" />
        <RowDefinition Height="100*" />
    </Grid.RowDefinitions>
    <Grid.ColumnDefinitions>
        <ColumnDefinition Width="33*" />
        <ColumnDefinition Width="Auto" />
        <ColumnDefinition Width="67*" />
    </Grid.ColumnDefinitions>

    <Button Content="Button No. 1" Grid.Row="0" Grid.Column="0" />
    <Button Content="Button No. 2" Grid.Row="1" Grid.Column="0" />
    <Button Content="Button No. 3" Grid.Row="2" Grid.Column="0" />

    <GridSplitter HorizontalAlignment="Center" Width="6"
                  Grid.Row="0" Grid.Column="1" Grid.RowSpan="3" />

    <Button Content="Button No. 4" Grid.Row="0" Grid.Column="2" />
    <Button Content="Button No. 5" Grid.Row="1" Grid.Column="2" />
    <Button Content="Button No. 6" Grid.Row="2" Grid.Column="2" />
 
</Grid>