Text1.Text = "Text1";
Text2.Text = "Text2";
split.Width = 3;

Text1.Background = new SolidColorBrush(Colors.Red);


Grid ingd = new Grid();
RowDefinition inrow1 = new RowDefinition();
ColumnDefinition inCol1 = new ColumnDefinition();
ColumnDefinition inCol2 = new ColumnDefinition();
ColumnDefinition inCol3 = new ColumnDefinition();
ingd.RowDefinitions.Add(inrow1);
ingd.ColumnDefinitions.Add(inCol1);
ingd.ColumnDefinitions.Add(inCol2);
ingd.ColumnDefinitions.Add(inCol3);

// Width set here as Star for the left textblock
inCol1.Width = new GridLength(10, GridUnitType.Star);
inCol2.Width = new GridLength(3, GridUnitType.Pixel);
inCol3.Width = new GridLength(0, GridUnitType.Auto);

ingd.Children.Add(Text1);
ingd.Children.Add(split);
ingd.Children.Add(Text2);

Grid.SetColumn(Text1, 0);
Grid.SetColumn(split, 1);
Grid.SetColumn(Text2, 2);

wrap.Children.Add(ingd);

Text2.Visibility = System.Windows.Visibility.Collapsed
split.Visibility = System.Windows.Visibility.Collapsed;

<Window x:Class="WpfApplication4.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="MainWindow" Height="350" Width="525">
    <Grid>
        <WrapPanel Name="wrap" >
        </WrapPanel>
        <Button Height="100" Click="Button_Click"></Button>
    </Grid>
 </Window>