A Recursively Splittable WPF Content Control Style for User Customizable Interfaces

<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
					xmlns:sys="clr-namespace:System;assembly=mscorlib"
					xmlns:winInter="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity"
					xmlns:hwpf="clr-namespace:HurWpfLib">
	
	<BooleanToVisibilityConverter x:Key="boolVisConverter"/>
	<hwpf:DoubleGridLengthConverter x:Key="splitPositionConverter"/>
	
    <!--The style which is applied to an unsplit view's inner border-->
    <Style x:Key="DefaultUnsplitBorderStyle" TargetType="Border">
        <Style.Setters>
            <Setter Property="Background" Value="LightBlue"/>
            <Setter Property="CornerRadius" Value="0"/>
        </Style.Setters>
        <Style.Triggers>
            <DataTrigger Binding="{Binding Path=IsSelected}" Value="False">
                <Setter Property="BorderBrush" Value="RoyalBlue"/>
                <Setter Property="BorderThickness" Value="1"/>
            </DataTrigger>
            <DataTrigger Binding="{Binding Path=IsSelected}" Value="True">
                <Setter Property="BorderBrush" Value="Red"/>
                <Setter Property="BorderThickness" Value="2"/>
            </DataTrigger>
        </Style.Triggers>
    </Style>
    
	<sys:Boolean x:Key="trueValue">True</sys:Boolean>
	
    <DataTemplate x:Key="UnsplitTemplate">
            <!--The elements in this template will appear in the content template of the styled ContentControl.
                Therefore, they make use of the content as their DataContext.-->
        <Border x:Name="viewBorder" Style="{StaticResource DefaultUnsplitBorderStyle}">
			<ContentPresenter x:Name="innerContentPresenter" Content="{Binding Path=InnerContent}"
					ContentTemplateSelector="{x:Static hwpf:RecursiveSplitViewModel.InnerContentTemplateSelector}">
			</ContentPresenter>
			<!--This should help an unsplit view to get its viewmodel selected if clicked or became the target of a drop action.-->
			<winInter:Interaction.Triggers>
				<winInter:EventTrigger EventName="PreviewMouseDown">
					<winInter:InvokeCommandAction Command="{Binding Path=SelectCommand, Mode=OneWay}" CommandParameter="{StaticResource trueValue}"/>
				</winInter:EventTrigger>
				<winInter:EventTrigger EventName="PreviewDrop">
					<winInter:InvokeCommandAction Command="{Binding Path=SelectCommand, Mode=OneWay}" CommandParameter="{StaticResource trueValue}"/>
				</winInter:EventTrigger>
			</winInter:Interaction.Triggers>
		</Border>
    </DataTemplate>

    <DataTemplate x:Key="HorizontalSplitTemplate">
        <!--The elements in this template will appear in the content template of the styled ContentControl.
                Therefore, they make use of the content as their DataContext.-->
        <Grid x:Name="splitViewGrid">
            <Grid.RowDefinitions>
					<!--The top panel height is bound to the SplitPosition property.
						I would love to be able to express SplitPosition as a fractional value (ranging from 0 to 1),
						but I just wasn't able to use the control size as a ConverterParameter.-->
				<RowDefinition Height="{Binding Path=SplitPosition, Mode=TwoWay, Converter={StaticResource splitPositionConverter}}"/>
                <RowDefinition Height="Auto"/>
                <RowDefinition Height="*"/>
            </Grid.RowDefinitions>

                <!--The splittable view associated with Child1 viewmodel object-->
            <ContentControl  Grid.Row="0" Style="{DynamicResource RecursiveSplitViewStyle}"
                    DataContext="{Binding Path=Child1}" x:Name="child1View"/>
                <!--The grid splitter object separating the child views.-->
            <GridSplitter  Grid.Row="1" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" ResizeDirection="Rows"
                           Height="{Binding Source={x:Static hwpf:RecursiveSplitViewModel.DefaultSplitterWidth}}"/>

                <!--The splittable view associated with Child2 viewmodel object-->
            <ContentControl  Grid.Row="2" Style="{DynamicResource RecursiveSplitViewStyle}"
                    DataContext="{Binding Path=Child2}" x:Name="child2View"/>
        </Grid>
    </DataTemplate>

    <DataTemplate x:Key="VerticalSplitTemplate">
        <!--The elements in this template will appear in the content template of the styled ContentControl.
                Therefore, they make use of the content as their DataContext.-->
        <Grid x:Name="splitViewGrid">
            <Grid.ColumnDefinitions>
				<!--The left panel width is bound to the SplitPosition property.
						I would love to be able to express SplitPosition as a fractional value (ranging from 0 to 1),
						but I just wasn't able to use the control size as a ConverterParameter.-->
				<ColumnDefinition Width="{Binding Path=SplitPosition, Mode=TwoWay, Converter={StaticResource splitPositionConverter}}"/>
                <ColumnDefinition Width="Auto"/>
                <ColumnDefinition Width="*"/>
            </Grid.ColumnDefinitions>

            <!--The splittable view associated with Child1 viewmodel object-->
            <ContentControl  Grid.Column="0" Style="{DynamicResource RecursiveSplitViewStyle}"
                    DataContext="{Binding Path=Child1}" x:Name="child1View"/>
            <!--The grid splitter object separating the child views.-->
            <GridSplitter  Grid.Column="1" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" ResizeDirection="Columns"
                           Width="{Binding Source={x:Static hwpf:RecursiveSplitViewModel.DefaultSplitterWidth}}"/>

            <!--The splittable view associated with Child2 viewmodel object-->
            <ContentControl  Grid.Column="2" Style="{DynamicResource RecursiveSplitViewStyle}"
                    DataContext="{Binding Path=Child2}" x:Name="child2View"/>
        </Grid>
    </DataTemplate>

	<!--I learned about pass enum values as parameters from http://social.msdn.microsoft.com/forums/en-US/wpf/thread/03e543f8-c8f5-4a1c-9348-91200c9c1091/-->
	<ContextMenu x:Key="splitViewContextMenu" x:Shared="True" x:Name="splitViewContextMenu">
		<MenuItem Header="Horizontal Split" Command="{Binding Path=SplitCommand}" CommandParameter="{x:Static hwpf:RecursiveSplitState.HorizontalSplit}"/>
		<MenuItem Header="Vertical Split" Command="{Binding Path=SplitCommand}" CommandParameter="{x:Static hwpf:RecursiveSplitState.VerticalSplit}"/>
	</ContextMenu>
	
    <!--A ContentControl with this style will have a RecursiveSplitViewModel object as its DataContext.
            It will also have this object as its Content, so that the elements in its current ContentTemplate
            will use it as their DataContext, as well.-->
    <Style x:Key="RecursiveSplitViewStyle" TargetType="{x:Type ContentControl}">
        
        <Style.Setters>
			<Setter Property="AllowDrop" Value="{Binding Path=IsEnabled}"/>
			<Setter Property="Content" Value="{Binding}"/>
        </Style.Setters>
        
        <Style.Triggers>
            <DataTrigger Binding="{Binding Path=SplitState}" Value="Unsplit">
                <Setter Property="ContentTemplate" Value="{StaticResource UnsplitTemplate}"/>
				<Setter Property="ContextMenu" Value="{StaticResource splitViewContextMenu}"/>
			</DataTrigger>
            <DataTrigger Binding="{Binding Path=SplitState}" Value="HorizontalSplit">
                <Setter Property="ContentTemplate" Value="{StaticResource HorizontalSplitTemplate}"/>
				<Setter Property="ContextMenu" Value="{x:Null}"/>
            </DataTrigger>
            <DataTrigger Binding="{Binding Path=SplitState}" Value="VerticalSplit">
                <Setter Property="ContentTemplate" Value="{StaticResource VerticalSplitTemplate}"/>
				<Setter Property="ContextMenu" Value="{x:Null}"/>
            </DataTrigger>
			
		</Style.Triggers>
    </Style>
    
</ResourceDictionary>