Neptune/Neptune/View/Controls/EditorHost.axaml

<UserControl xmlns="https://github.com/avaloniaui"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mvvm="clr-namespace:Glitonea.Mvvm;assembly=Glitonea"
             xmlns:vm="clr-namespace:Neptune.ViewModel.Controls"
             xmlns:vme="clr-namespace:Neptune.ViewModel.Controls.Editors"
             xmlns:editors="clr-namespace:Neptune.View.Controls.Editors"
             xmlns:controls="clr-namespace:Neptune.View.Controls"
             x:Class="Neptune.View.Controls.EditorHost"
             DataContext="{mvvm:DataContextSource vm:EditorHostViewModel}">
    <Grid>
        <ContentPresenter HorizontalAlignment="Stretch"
                          VerticalAlignment="Stretch"
                          HorizontalContentAlignment="Stretch"
                          VerticalContentAlignment="Stretch"
                          Background="{StaticResource NeptuneDarkBackgroundBrush}"
                          Content="{Binding $parent[controls:EditorHost].DataContext.CurrentConfigEditor}"
                          IsVisible="{Binding $parent[controls:EditorHost].DataContext.IsEditorAvailable}">
            <ContentPresenter.DataTemplates>
                <DataTemplate DataType="vme:XteaKeysEditorViewModel">
                    <editors:XteaKeysEditor />
                </DataTemplate>

                <DataTemplate DataType="{x:Null}">

                </DataTemplate>
            </ContentPresenter.DataTemplates>
        </ContentPresenter>

        <Grid ColumnDefinitions="Auto,Auto,Auto"
              RowDefinitions="Auto,Auto"
              HorizontalAlignment="Center"
              VerticalAlignment="Center"
              IsVisible="{Binding !IsEditorAvailable}">
            <TextBlock Grid.Column="0"
                       Grid.Row="0"
                       HorizontalAlignment="Center"
                       FontSize="16"
                       Text="And here I would display the editor for "
                       Opacity="0.4" />

            <TextBlock Grid.Column="1"
                       Grid.Row="0"
                       HorizontalAlignment="Center"
                       FontSize="16"
                       Text="{Binding SelectedConfigMember.FriendlyName}"
                       Opacity="0.8" />

            <TextBlock Grid.Column="2"
                       Grid.Row="0"
                       HorizontalAlignment="Center"
                       FontSize="16"
                       Text="."
                       Opacity="0.4" />

            <TextBlock Grid.ColumnSpan="3"
                       Grid.Row="1"
                       HorizontalAlignment="Center"
                       FontSize="16"
                       Text="IF I HAD ONE"
                       Foreground="Red"
                       FontWeight="800"
                       Opacity="0.8" />
        </Grid>
    </Grid>
</UserControl>