RichTextBox in DataTemplate not filling

Question

I have a RichTextBox in a DataTemplate and it is not filling the space while other controls are. It is as if the RichTextBox is set to a Width="1" Here is my DataTemplate;

<DataTemplate x:Key="MyDataTemplate" >
   <StackPanel>
       <RichTextBox />
       <TextBox />
   </StackPanel>
</DataTemplate >

This is what it looks like if I type "12345" with no spaces or returns;

Also here is how I use the DataTemplate ;

<ListBox  Margin="2" SelectionMode="Single" ItemTemplate="{StaticResource MyDataTemplate}"/>

Note: If I sent the RichTextBox MinWidth to something it does make it better (for example "12345" would appear correctly), but still does not fill the space.

Answer 1

The template:

    <DataTemplate x:Key="MyDataTemplate" >
        <StackPanel x:Name="Panel">
            <RichTextBox Width="{Binding ElementName=Panel, Path=ActualWidth}" />
            <TextBox />
        </StackPanel>
    </DataTemplate >

And your list:

<ListBox ItemTemplate="{StaticResource MyDataTemplate}"
         HorizontalContentAlignment="Stretch"
         ItemsSource="{Binding }"/>