gistfile1.xml

<Application x:Class="HearthCap.App"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:converters="clr-namespace:HearthCap.UI.Converters"
             xmlns:startUp="clr-namespace:HearthCap.StartUp">
    <Application.Resources>
        <ResourceDictionary>
            <ResourceDictionary.MergedDictionaries>
                <ResourceDictionary Source="pack://application:,,,/MahApps.Metro;component/Styles/Controls.xaml" />
                <ResourceDictionary Source="pack://application:,,,/MahApps.Metro;component/Styles/Fonts.xaml" />
                <ResourceDictionary Source="pack://application:,,,/MahApps.Metro;component/Styles/Colors.xaml" />
                <ResourceDictionary Source="pack://application:,,,/MahApps.Metro;component/Styles/Accents/Blue.xaml" />
                <ResourceDictionary Source="pack://application:,,,/MahApps.Metro;component/Styles/Accents/BaseLight.xaml" />
                <ResourceDictionary>
                    <converters:BitmapConverter x:Key="imageConverter"></converters:BitmapConverter>
                    <converters:BooleanToVisibilityConverter x:Key="booleanToVisibility"
                                                             True="Visible"
                                                             False="Collapsed" />
                    <converters:BooleanToVisibilityConverter x:Key="booleanToVisibilityInverse"
                                                             True="Collapsed"
                                                             False="Visible" />
                    <converters:NullToCollapsedConverter x:Key="nullToCollapsed" />
                </ResourceDictionary>
                <ResourceDictionary>
                    <startUp:AppBootstrapper x:Key="bootstrapper" />
                </ResourceDictionary>
            </ResourceDictionary.MergedDictionaries>
            <converters:NullToBooleanConverter x:Key="nullToBoolean" />
            <converters:InvertBooleanConverter x:Key="invertBoolean" />
            <converters:HeroKeyToImageConverter x:Key="heroKeyToImage" />
            <converters:EnumNameConverter x:Key="enumNameConverter" />
            <converters:TruncateConverter x:Key="truncateText" />
        </ResourceDictionary>
    </Application.Resources>
</Application>

A window:


<metro:MetroWindow x:Class="HearthCap.Shell.ShellView"
                   xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                   xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                   xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
                   xmlns:cal="http://www.caliburnproject.org"
                   xmlns:metro="http://metro.mahapps.com/winfx/xaml/controls"
                   xmlns:i="http://schemas.microsoft.com/expression/2010/interactivity"
                   xmlns:behaviours="http://metro.mahapps.com/winfx/xaml/shared"
                   xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
                   xmlns:shell="clr-namespace:HearthCap.Shell"
                   mc:Ignorable="d"
                   d:DataContext="{d:DesignInstance Type=shell:ShellViewModel, IsDesignTimeCreatable=False}"
                   cal:Bind.AtDesignTime="True"
                   WindowStartupLocation="CenterScreen"
                   Width="800"
                   Height="600"
                   MinWidth="800"
                   MinHeight="600"
                   ShowIconOnTitleBar="True"
                   Icon="\Resources\hearthstone_icon.png">