UWP reference control outside of data template - xaml

Question

I'm trying to create a listview that has column headers and the lists fields mimics the width of its corresponding header. No bindings fail but the textblocks width in the data template don't match up with their headers width. I'm guessing because the data template can't find the element. Any ideas to get this to work?
<Grid Grid.Column="1" Grid.Row="1" x:Name="listViewHeaders" Height="50" VerticalAlignment="Top" Margin="10,0" >
<Grid.ColumnDefinitions>
<ColumnDefinition />
<ColumnDefinition />
<ColumnDefinition />
</Grid.ColumnDefinitions>
<!--<controls:CustomGridSplitter/>-->
<TextBlock x:Name="nameHeader" Grid.Column="0" Text="Name" />
<TextBlock x:Name="typeHeader" Grid.Column="1" Text="Type" />
<TextBlock x:Name="colorHeader" Grid.Column="2" Text="Color" />
</Grid>
<ListView x:Name="ListView" Grid.Row="1" Grid.Column="1" Background="#FF494949" Margin="10,50,10,0" ItemsSource="{Binding CurrentCardList}">
<ListView.ItemTemplate>
<DataTemplate>
<Grid Width="{Binding ActualWidth, ElementName=ListView}">
<!--<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto" />
<ColumnDefinition Width="Auto" />
<ColumnDefinition Width="Auto" />
</Grid.ColumnDefinitions>-->
<StackPanel Orientation="Horizontal">
<TextBlock Grid.Column="0" Width="{Binding ActualWidth, ElementName=nameHeader}" Text="{Binding Name}" />
<TextBlock Grid.Column="1" Width="{Binding ActualWidth, ElementName=typeHeader}" Text="{Binding Type}" />
<TextBlock Grid.Column="2" Width="{Binding ActualWidth, ElementName=colorHeader}" Text="{Binding Color}" />
</StackPanel>
</Grid>
</DataTemplate>
</ListView.ItemTemplate>
<ListView.ItemContainerStyle>
<Style TargetType="ListViewItem">
<Setter Property="HorizontalContentAlignment" Value="Stretch" />
</Style>
</ListView.ItemContainerStyle>
</ListView>

Answer 1

The bindings work fine. But you're assuming that TextBlock elements in the header row will fill out the entire table cell, which they won't. They only fill as much space as much text they contain. In your case that's about 30px. You can find this information by using the Live Visual Tree feature of VS 2015.
You can solve the problem by wrapping the header TextBlock elements in another element that will fill out all available space, such as Border. Here's the solution:
<Grid Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
<Grid x:Name="listViewHeaders" Height="50" VerticalAlignment="Top" Margin="10,0" >
<Grid.ColumnDefinitions>
<ColumnDefinition />
<ColumnDefinition />
<ColumnDefinition />
</Grid.ColumnDefinitions>
<!--<controls:CustomGridSplitter/>-->
<Border Background="Blue" HorizontalAlignment="Stretch" Grid.Column="0" x:Name="nameHeader">
<TextBlock Text="Name" />
</Border>
<Border Background="Red" x:Name="typeHeader" Grid.Column="1">
<TextBlock Text="Type" HorizontalAlignment="Stretch" />
</Border>
<Border Background="Yellow" x:Name="colorHeader" Grid.Column="2">
<TextBlock Text="Color" HorizontalAlignment="Stretch" />
</Border>
</Grid>
<ListView x:Name="ListView" Background="#FF494949" Margin="10,50,10,0" ItemsSource="{Binding CurrentCardList}">
<ListView.ItemTemplate>
<DataTemplate>
<Grid Width="{Binding ActualWidth, ElementName=ListView}">
<!--<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto" />
<ColumnDefinition Width="Auto" />
<ColumnDefinition Width="Auto" />
</Grid.ColumnDefinitions>-->
<StackPanel Orientation="Horizontal">
<TextBlock Grid.Column="0" Width="{Binding ActualWidth, ElementName=nameHeader}" Text="{Binding Name}" />
<TextBlock Grid.Column="1" Width="{Binding ActualWidth, ElementName=typeHeader}" Text="{Binding Type}" />
<TextBlock Grid.Column="2" Width="{Binding ActualWidth, ElementName=colorHeader}" Text="{Binding Color}" />
</StackPanel>
</Grid>
</DataTemplate>
</ListView.ItemTemplate>
<ListView.ItemContainerStyle>
<Style TargetType="ListViewItem">
<Setter Property="HorizontalContentAlignment" Value="Stretch" />
</Style>
</ListView.ItemContainerStyle>
</ListView>
</Grid>
This will create the following effect, which I believe is what you're after.
Here's the link to the complete solution - http://1drv.ms/1eUzLHl