WPF Diagram Designer - Part 4

<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" >

  <ResourceDictionary.MergedDictionaries>
    <ResourceDictionary Source="Shared.xaml" />
  </ResourceDictionary.MergedDictionaries>

  <!-- SimpleStyles: Expander -->
    <Style TargetType="ToggleButton">
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="ToggleButton">
                    <Border Name="Border" 
                            CornerRadius="2,0,0,0"
                            Background="Transparent"
                            BorderBrush="{StaticResource NormalBorderBrush}"
                            BorderThickness="0,0,1,0">
                        <Path Name="Arrow"
                              Fill="{StaticResource GlyphBrush}"
                              HorizontalAlignment="Center"
                              VerticalAlignment="Center"
                              Data="M 0 0 L 4 4 L 8 0 Z"/>
                    </Border>
                    <ControlTemplate.Triggers>
                        <Trigger Property="ToggleButton.IsMouseOver" Value="true">
                            <Setter TargetName="Border" Property="Background" Value="{StaticResource DarkBrush}" />
                        </Trigger>
                        <Trigger Property="IsPressed" Value="true">
                            <Setter TargetName="Border" Property="Background" Value="{StaticResource PressedBrush}" />
                        </Trigger>
                        <Trigger Property="IsChecked" Value="true">
                            <Setter TargetName="Arrow" Property="Data" Value="M 0 4 L 4 0 L 8 4 Z" />
                        </Trigger>
                        <Trigger Property="IsEnabled" Value="False">
                            <Setter TargetName="Border" Property="Background" Value="{StaticResource DisabledBackgroundBrush}" />
                            <Setter TargetName="Border" Property="BorderBrush" Value="{StaticResource DisabledBorderBrush}" />
                            <Setter Property="Foreground" Value="{StaticResource DisabledForegroundBrush}"/>
                            <Setter TargetName="Arrow" Property="Fill" Value="{StaticResource DisabledForegroundBrush}" />
                        </Trigger>
                    </ControlTemplate.Triggers>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>
    

    <Style TargetType="Expander">
    <Setter Property="Control.Foreground" Value="#4C4C4C"/>
    <Setter Property="Template">
      <Setter.Value>
        <ControlTemplate TargetType="Expander">
          <Grid>
            <Grid.RowDefinitions>
              <RowDefinition Height="Auto"/>
              <RowDefinition Name="ContentRow" Height="0"/>
            </Grid.RowDefinitions>
            <Border Name="Border" 
                    Grid.Row="0" 
                    Background="{StaticResource LightBrush}"
                    BorderBrush="{StaticResource NormalBorderBrush}"
                    BorderThickness="1" 
                    CornerRadius="2,2,0,0" >
              <Grid>
                <Grid.ColumnDefinitions>
                  <ColumnDefinition Width="20" />
                  <ColumnDefinition Width="*" />
                </Grid.ColumnDefinitions>
                <ToggleButton IsChecked="{Binding Path=IsExpanded,Mode=TwoWay,
                              RelativeSource={RelativeSource TemplatedParent}}"
                              OverridesDefaultStyle="True"                   
                              Background="{StaticResource NormalBrush}" />
                <ContentPresenter Grid.Column="1"
                                  Margin="4" 
                                  ContentSource="Header" 
                                  RecognizesAccessKey="True" />
              </Grid>
            </Border>
            <Border Name="Content" 
                    Grid.Row ="1" 
                    Background="{StaticResource WindowBackgroundBrush}"
                    BorderBrush="{StaticResource SolidBorderBrush}" 
                    BorderThickness="1,0,1,1" 
                    CornerRadius="0,0,2,2" >
              <ContentPresenter Margin="4" />
            </Border>
          </Grid>
          <ControlTemplate.Triggers>
            <Trigger Property="IsExpanded" Value="True">
              <Setter TargetName="ContentRow" Property="Height" Value="{Binding ElementName=Content,Path=DesiredHeight}" />
            </Trigger>
            <Trigger Property="IsEnabled" Value="False">
              <Setter TargetName="Border" Property="Background" Value="{StaticResource DisabledBackgroundBrush}" />
              <Setter TargetName="Border" Property="BorderBrush" Value="{StaticResource DisabledBorderBrush}" />
              <Setter Property="Foreground" Value="{StaticResource DisabledForegroundBrush}"/>
            </Trigger>
          </ControlTemplate.Triggers>
        </ControlTemplate>
      </Setter.Value>
    </Setter>
  </Style>
</ResourceDictionary>