How to support re-sizing of DataGridRowHeader column in DataGrid

Question

I would like to allow re-sizing of zeroth column of dataGrid, the column which contains the SelectAll button and row headers -

Image taken from - WPF Toolkit DataGrid, Part II – Custom styling

Answer 1

Try this...

XAML:

   <tk:DataGrid x:Name="MyDataGrid"
                RowHeaderWidth="15"
                ItemsSource="{StaticResource MyData}"
                AutoGenerateColumns="False">
        <tk:DataGrid.Columns>
            <tk:DataGridTextColumn Binding="{Binding ID}">
                <tk:DataGridTextColumn.HeaderTemplate>
                    <DataTemplate>
                        <DockPanel>
                            <GridSplitter
                                DockPanel.Dock="Left"
                                VerticalAlignment="Stretch"
                                HorizontalAlignment="Left" Width="2"
                                DragDelta="GridSplitter_DragDelta"/>
                            <TextBlock Text="ID" DockPanel.Dock="Right"/>
                        </DockPanel>
                    </DataTemplate>
                </tk:DataGridTextColumn.HeaderTemplate>
            </tk:DataGridTextColumn>
            <tk:DataGridTextColumn Header="Name"
                                   Binding="{Binding Name}">
            </tk:DataGridTextColumn>
        </tk:DataGrid.Columns>
    </tk:DataGrid>

Code Behind:

     private void GridSplitter_DragDelta
        (object sender,
         System.Windows.Controls.Primitives.DragDeltaEventArgs e)
    {
        if (MyDataGrid.RowHeaderWidth + e.HorizontalChange >= 15)
        {
            MyDataGrid.RowHeaderWidth = MyDataGrid.RowHeaderWidth + e.HorizontalChange;
        }
    }

You could override RowHeaderTemplate and do this exact grid splitter docked to right hand side. But for me docking it to left on the first column header worked the best!