Caliburn - Modules, Windows, and Actions

<Window x:Class="emx.tcp.caliburn.loading.shell.Views.ShellView"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:cal="http://www.caliburnproject.org"
    xmlns:shared.actions="clr-namespace:emx.tcp.caliburn.loading.shared.Actions;assembly=emx.tcp.caliburn.loading.shared"
    xmlns:Controls="clr-namespace:Caliburn.WPF.ApplicationFramework.Controls;assembly=Caliburn.WPF.ApplicationFramework"
    Title="ShellView" Height="432" Width="304">
    <DockPanel>
        <Grid>
            <StackPanel x:Name="LayoutRoot">
                <DockPanel LastChildFill="True">
                    <Label 
                        DockPanel.Dock="Left"
                        Content="Target of Module: "/>
                    <ComboBox 
                        x:Name="HostComboBox" 
                        DockPanel.Dock="Right"
                        SelectedIndex="0">
                        <ComboBoxItem>In a Window</ComboBoxItem>
                        <ComboBoxItem>Embedded here</ComboBoxItem>
                    </ComboBox>
                </DockPanel>
                <Button 
                    cal:Message.Attach="ShowModuleA(HostComboBox.SelectedIndex)"
                    Content="Module A - Persons"/>
                <Button 
                    cal:Message.Attach="ShowModuleB(HostComboBox.SelectedIndex)"
                    Content="Module B - Tasks"/>
                <TextBlock Text="{Binding CurrentPresenter.DisplayName}"
                       HorizontalAlignment="Center"
                       FontSize="18"
                       Foreground="CornflowerBlue"
                       Margin="5" />
                <Controls:TransitionPresenter x:Name="CurrentPresenter">
                    <cal:Action.TargetWithoutContext >
                        <shared.actions:CRUDAction />
                    </cal:Action.TargetWithoutContext >
                </Controls:TransitionPresenter>
            </StackPanel>
        </Grid>
    </DockPanel>
</Window>