Let TextBox fill remaining Space in Grid

I have a ListBox that contains a Grid. The Grid has a Label Column, a GridSplitter and a TextBox Column. How can I make the Grid take up the entire Width of the ListBox and make the TextBox use the entire space of the Grid Column? ``` <Grid> <ListBox x:Name="myList" Margin="4" ItemsSource="{Binding Path=Parameter}" MinHeight="60" Grid.IsSharedSizeScope="True" HorizontalAlignment="Stretch" > <ListBox.ItemTemplate> <DataTemplate> <Grid x:Name="parameterGrid" HorizontalAlignment="Stretch"> <Grid.ColumnDefinitions> <ColumnDefinition x:Name="labelColumn" Width="Auto" SharedSizeGroup="LabelColumn"/> <ColumnDefinition x:Name="splitterColumn" Width="5"/> <ColumnDefinition x:Name="textColumn" Width="*"/> </Grid.ColumnDefinitions> <TextBlock Text="{Binding Path=Key}" Grid.Column="0"/> <GridSplitter Grid.Column="1" VerticalAlignment="Stretch" HorizontalAlignment="Stretch"/> <TextBox Grid.Column="2" Text="{Binding Path=Value, UpdateSourceTrigger=LostFocus}" IsEnabled="{Binding ElementName=_view, Path=DataContext.IsEditEnabled}"> </TextBox> </Grid> </DataTemplate> </ListBox.ItemTemplate> </ListBox> </Grid> ``` The Parameter is just to demonstrate the idea: ``` public class Parameter { public string Key { get; set; } public string Value { get; set; } public Parameter(string key, string value) { Key = key; Value = value; } } ```