WPF - GridSplitter with three columns

Question

I have an app with grid with 3 columns. The grid splitter between the first and second columns works just fine. To get the splitter over to be between the second and third columns I made a column for the splitter. (So now the the third column is really the fourth.)

When I resize the other columns also shrink. I assume that is because I have them set to be relative sized. But I don't know how to fix it.

Here is a XAML Pad Ready example of my issue. Plug this into XAML pad and then try to resize the last column to be smaller.

<Page
  xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
    <Grid>
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="1*" />
            <ColumnDefinition Width="1*" />
            <ColumnDefinition Width="Auto" />
            <ColumnDefinition Width="1*" />
        </Grid.ColumnDefinitions>
        <StackPanel Background="#feca00" Grid.Column="0">
            <TextBlock FontSize="35" Foreground="#58290A"
                   TextWrapping="Wrap">Left Hand Side</TextBlock>
        </StackPanel>
        <GridSplitter Width="10" />
        <Border CornerRadius="10" BorderBrush="#58290A"
              BorderThickness="5" Grid.Column="1">
            <TextBlock FontSize="25" Margin="20" Foreground="#FECA00"
                   TextWrapping="Wrap">Right Hand Side</TextBlock>
        </Border>
        <GridSplitter Grid.Column="2" HorizontalAlignment="Right"  VerticalAlignment="Stretch" Width="5"></GridSplitter>
        <TabControl Grid.Column="3" Name="tabControl1">
            <TabItem Header="Add Links" Name="tabAddLinks">
                <Grid></Grid>
            </TabItem>
        </TabControl>
    </Grid>
</Page> 

Thanks for the help!

---

EDIT: It was suggested that having both splitters in their own columns might fix it. I tried that and now the first splitter also shrinks the columns like the second splitter does.

Here is the XAML Pad code for that example:

<Page
  xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
    <Grid>
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="1*" />
            <ColumnDefinition Width="Auto" />
            <ColumnDefinition Width="1*" />
            <ColumnDefinition Width="Auto" />
            <ColumnDefinition Width="1*" />
        </Grid.ColumnDefinitions>
        <StackPanel Background="#feca00" Grid.Column="0">
            <TextBlock FontSize="35" Foreground="#58290A"
                   TextWrapping="Wrap">Left Hand Side</TextBlock>
        </StackPanel>
        <GridSplitter Grid.Column="1" HorizontalAlignment="Right"  VerticalAlignment="Stretch" Width="5"></GridSplitter>
        <Border CornerRadius="10" BorderBrush="#58290A"
              BorderThickness="5" Grid.Column="2">
            <TextBlock FontSize="25" Margin="20" Foreground="#FECA00"
                   TextWrapping="Wrap">Right Hand Side</TextBlock>
        </Border>
        <GridSplitter Grid.Column="3" HorizontalAlignment="Right"  VerticalAlignment="Stretch" Width="5"></GridSplitter>
        <TabControl Grid.Column="4" Name="tabControl1">
            <TabItem Header="Add Links" Name="tabAddLinks">
                <Grid></Grid>
            </TabItem>
        </TabControl>
    </Grid>
</Page> 

Answer 1

Try setting HorizontalAlignment="Center" for both splitters - no idea why having it set to "Right" should cause the behaviour to go so screwy, but changing it worked for me :)

Answer 2

A GridSplitter should be placed within its own Column in a Grid. I'm not sure I understand your issue entirely, but I suggest you try creating a Grid with 5 ColumnDefinitions. Use columns 1 and 2 to place the GridSplitters and columns 0, 2 and 4 for content.

The GridSplitter MSDN doc has a sample on how to do this.

<Grid.ColumnDefinitions>
  <ColumnDefinition/>
  <ColumnDefinition Width="Auto" />
  <ColumnDefinition/>
</Grid.ColumnDefinitions>
...
<GridSplitter Grid.Column="1"
          HorizontalAlignment="Center"
          VerticalAlignment="Stretch"
          Background="Black" 
          ShowsPreview="True"
          Width="5"
          />