ProxySU/ProxySU_Core/Views/TextBoxWindow.xaml

<metro:MetroWindow x:Class="ProxySU_Core.Views.TextBoxWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:ProxySU_Core.Views"
        xmlns:metro="http://metro.mahapps.com/winfx/xaml/controls"
        mc:Ignorable="d"
        Title="TextBoxWindow" Height="450" Width="800">
    <Grid>
        <TextBox Margin="20"
                 Text="{Binding Path=Message}"
                 TextWrapping="Wrap"
                 FontSize="14"
                 Style="{StaticResource MahApps.Styles.TextBox}" />
    </Grid>
</metro:MetroWindow>