<Application.Resources>

    <ResourceDictionary>

      <ResourceDictionary.MergedDictionaries>

        <!-- MahApps.Metro resource dictionaries. Make sure that all file names are Case Sensitive! -->

        <ResourceDictionary Source="pack://application:,,,/MahApps.Metro;component/Styles/Controls.xaml" />

        <ResourceDictionary Source="pack://application:,,,/MahApps.Metro;component/Styles/Fonts.xaml" />

        <!-- Theme setting -->

        <ResourceDictionary Source="pack://application:,,,/MahApps.Metro;component/Styles/Themes/Light.Blue.xaml" />

      </ResourceDictionary.MergedDictionaries>

    </ResourceDictionary>

</Application.Resources>

xmlns:mah="clr-namespace:MahApps.Metro.Controls;assembly=MahApps.Metro"

或者

xmlns:mah="http://metro.mahapps.com/winfx/xaml/controls"

<mah:MetroWindow x:Class="WpfApp8.StartView"

        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:mah="clr-namespace:MahApps.Metro.Controls;assembly=MahApps.Metro"

         xmlns:cal="http://www.caliburnproject.org" 

        xmlns:local="clr-namespace:WpfApp8"

        mc:Ignorable="d"

        GlowBrush="{DynamicResource MahApps.Brushes.Accent}"

        ResizeMode="CanResizeWithGrip"

        Title="StartView" Height="300" Width="600" WindowStartupLocation="CenterScreen">

    <StackPanel>

        <TextBox Name="TextContent"/>

        <Button x:Name="testBtn" Content="testBtn"   Background="LightCyan"/>

        <ListBox Name="ListBoxItems"  MinHeight="230" Background="LightGray"

                 cal:Message.Attach="[Event selectionChanged] = [Action ListBoxItems_selectionChanged($source,$eventArgs)];

                                     [Event MouseUp]=[ListBoxItems_MouseUp($source,$eventArgs)]"

 />

    </StackPanel>

</mah:MetroWindow>

using MahApps.Metro.Controls;

namespace WpfApp8

{

    /// <summary>

    /// StartView.xaml 的交互邏輯

    /// </summary>

    public partial class StartView : MetroWindow

    {

        public StartView()

        {

            InitializeComponent();

        }

    }

}