WPF Grid.IsSharedSizeScope between two parent controls?

I have a situation where I need to share the width of a column between grids in two group boxes, the XAML looks something like this:

<GroupBox Header="Box A">
        <StackPanel Orientation="Horizontal">
            <!-- Labels -->
            <Grid>
                <Grid.ColumnDefinitions>
                    <ColumnDefinition SharedSizeGroup="Labels"></ColumnDefinition>
                </Grid.ColumnDefinitions>
                <Grid.RowDefinitions>
                    <RowDefinition SharedSizeGroup="Rows"></RowDefinition>
                </Grid.RowDefinitions>

                <Label Grid.Column="0" Grid.Row="0">Label A</Label>
            </Grid>

            <!-- Fields -->
            <ItemsControl Grid.IsSharedSizeScope="True" ItemsSource="{Binding Items}">
                <ItemsControl.ItemsPanel>
                    <ItemsPanelTemplate>
                        <StackPanel Orientation="Horizontal"></StackPanel>
                    </ItemsPanelTemplate>
                </ItemsControl.ItemsPanel>
                <ItemsControl.ItemTemplate>
                    <DataTemplate>
                        <Grid>
                            <Grid.RowDefinitions>
                                <RowDefinition SharedSizeGroup="Rows"></RowDefinition>
                            </Grid.RowDefinitions>

                            <TextBox Text="{Binding PropertyA}"></TextBox>
                        </Grid>
                    </DataTemplate>
                </ItemsControl.ItemTemplate>
            </ItemsControl>
        </StackPanel>
    </GroupBox>

    <GroupBox Header="Box B">
        <StackPanel Orientation="Horizontal">
            <!-- Labels -->
            <Grid>
                <Grid.ColumnDefinitions>
                    <ColumnDefinition SharedSizeGroup="Labels"></ColumnDefinition>
                </Grid.ColumnDefinitions>
                <Grid.RowDefinitions>
                    <RowDefinition SharedSizeGroup="Rows"></RowDefinition>
                </Grid.RowDefinitions>

                <Label Grid.Column="0" Grid.Row="0">Label B</Label>
            </Grid>

            <!-- Fields -->
            <ItemsControl Grid.IsSharedSizeScope="True" ItemsSource="{Binding Items}">
                <ItemsControl.ItemsPanel>
                    <ItemsPanelTemplate>
                        <StackPanel Orientation="Horizontal"></StackPanel>
                    </ItemsPanelTemplate>
                </ItemsControl.ItemsPanel>
                <ItemsControl.ItemTemplate>
                    <DataTemplate>
                        <Grid>
                            <Grid.RowDefinitions>
                                <RowDefinition SharedSizeGroup="Rows"></RowDefinition>
                            </Grid.RowDefinitions>

                            <TextBox Text="{Binding PropertyB}"></TextBox>
                        </Grid>
                    </DataTemplate>
                </ItemsControl.ItemTemplate>
            </ItemsControl>
        </StackPanel>
    </GroupBox>

I have tried setting Grid.IsSharedSizeScope to true on both the StackPanel and GroupBox containing the child grids, but this did not work. I was wondering what approach I should take in this situation to share the size between the Grid column definitions with the SharedSizeGroup of 'Labels'?

Thanks,

Alex.

Surround your two GroupBoxes with a Grid and set the Grid.IsSharedSizeScope.

<Page xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
      xmlns:sys="clr-namespace:System;assembly=mscorlib"
      xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
  <Grid Grid.IsSharedSizeScope="True">
    <Grid.Resources>
      <x:Array x:Key="xItems" Type="sys:String">
        <sys:String>Hello</sys:String>
        <sys:String>World ddd</sys:String>
      </x:Array>
      <x:Array x:Key="xItems2" Type="sys:String">
        <sys:String>Hello long fsdfhuzweb kbhui</sys:String>
        <sys:String>World</sys:String>
      </x:Array>
    </Grid.Resources>

    <Grid.ColumnDefinitions>
      <ColumnDefinition Width="*"/>
      <ColumnDefinition Width="*"/>
    </Grid.ColumnDefinitions>

    <GroupBox Grid.Column="0" Header="Box A">
      <StackPanel Orientation="Horizontal">
        <!-- Labels -->
        <Grid>
          <Grid.ColumnDefinitions>
            <ColumnDefinition SharedSizeGroup="Labels" />
          </Grid.ColumnDefinitions>
          <Label Grid.Column="0" Grid.Row="0">Label A</Label>
        </Grid>
        <!-- Fields -->
        <ItemsControl ItemsSource="{Binding Source={StaticResource xItems}}">
          <ItemsControl.ItemsPanel>
            <ItemsPanelTemplate>
              <StackPanel Orientation="Horizontal" />
            </ItemsPanelTemplate>
          </ItemsControl.ItemsPanel>
          <ItemsControl.ItemTemplate>
            <DataTemplate>
              <Grid>
                <Grid.ColumnDefinitions>
                  <ColumnDefinition SharedSizeGroup="Fields" />
                </Grid.ColumnDefinitions>
                <Grid.RowDefinitions>
                  <RowDefinition SharedSizeGroup="Rows" />
                </Grid.RowDefinitions>
                <TextBox Text="{Binding Mode=OneWay}" />
              </Grid>
            </DataTemplate>
          </ItemsControl.ItemTemplate>
        </ItemsControl>
      </StackPanel>
    </GroupBox>

    <GroupBox Grid.Column="1" Header="Box B">
      <StackPanel Orientation="Horizontal">
        <!-- Labels -->
        <Grid>
          <Grid.ColumnDefinitions>
            <ColumnDefinition SharedSizeGroup="Labels" />
          </Grid.ColumnDefinitions>
          <Grid.RowDefinitions>
            <RowDefinition SharedSizeGroup="Rows" />
          </Grid.RowDefinitions>
          <Label Grid.Column="0" Grid.Row="0">Label B long</Label>
        </Grid>
        <!-- Fields -->
        <ItemsControl ItemsSource="{Binding Source={StaticResource xItems2}}">
          <ItemsControl.ItemsPanel>
            <ItemsPanelTemplate>
              <StackPanel Orientation="Horizontal" />
            </ItemsPanelTemplate>
          </ItemsControl.ItemsPanel>
          <ItemsControl.ItemTemplate>
            <DataTemplate>
              <Grid>
                <Grid.ColumnDefinitions>
                  <ColumnDefinition SharedSizeGroup="Fields" />
                </Grid.ColumnDefinitions>
                <Grid.RowDefinitions>
                  <RowDefinition SharedSizeGroup="Rows" />
                </Grid.RowDefinitions>
                <TextBox Text="{Binding Mode=OneWay}" />
              </Grid>
            </DataTemplate>
          </ItemsControl.ItemTemplate>
        </ItemsControl>
      </StackPanel>
    </GroupBox>
  </Grid>
</Page>

Hope this helps.