MainWindowView

<controls:MetroWindow x:Class="Margo.UI.View.MainWindowView"
                      xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                      xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                      xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
                      xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
                      xmlns:views="clr-namespace:Margo.UI.View"
                      xmlns:vm="clr-namespace:Margo.UI.ViewModel"
                      xmlns:controls="http://metro.mahapps.com/winfx/xaml/controls"
                      mc:Ignorable="d"
                      Title="MainWindowView" Height="300" Width="500"
                      GlowBrush="{DynamicResource AccentColorBrush}">
    <Window.DataContext>
        <vm:MainWindowViewModel />
    </Window.DataContext>
    <Window.Resources>
        <DataTemplate DataType="{x:Type vm:ShoppingListViewModel}">
            <views:ShoppingListView />
        </DataTemplate>
        <DataTemplate DataType="{x:Type vm:ProductsViewModel}">
            <views:ProductsView />
        </DataTemplate>
        <DataTemplate DataType="{x:Type vm:AddProductViewModel}">
            <views:AddProductView/>
        </DataTemplate>
    </Window.Resources>
    <Grid Background="White">
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="150" />
            <ColumnDefinition />
            <ColumnDefinition />
        </Grid.ColumnDefinitions>
        <Grid.RowDefinitions>
            <RowDefinition />
            <RowDefinition />
            <RowDefinition />
        </Grid.RowDefinitions>
        <StackPanel x:Name="NavPanel"
                    Grid.Row="0"
                    Grid.Column="0"
                    Margin="10,10"
                    Background="DarkGray">
            <Button Content="Shopping List"
                    Command="{Binding NavCommand}"
                    CommandParameter="shoppingList" />
            <Button Content="Products"
                    Command="{Binding NavCommand}"
                    CommandParameter="products" />
        </StackPanel>

        <ContentControl Grid.Column="1"
                        Grid.Row="0"
                        Grid.ColumnSpan="2"
                        Grid.RowSpan="3"
                        Content="{Binding CurrentViewModel}" />
    </Grid>
</controls:MetroWindow>