MainWindow.xaml

<Window
        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:local="clr-namespace:VECTO3GUI2020"
        xmlns:Implementation="clr-namespace:VECTO3GUI2020.ViewModel.Implementation" x:Class="VECTO3GUI2020.MainWindow"
        mc:Ignorable="d"
        Title="Vecto" Height="450" Width="820"
        WindowStartupLocation="CenterScreen">



    <Grid>
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="1*"/>
        </Grid.ColumnDefinitions>
        <Grid.RowDefinitions>
            <RowDefinition Height="20"/>
            <RowDefinition Height="1.5*"/>
            <RowDefinition Height="1*"/>
        </Grid.RowDefinitions>

        <Grid Grid.Row="0" Margin="0,0,0,0">
            <StackPanel Orientation="Vertical">
                <Menu IsMainMenu="True">
                    <MenuItem Header="File" VerticalAlignment="Center">
                        <MenuItem Header="Settings" Command="{Binding OpenSettings}"/>
                        <MenuItem Header="New File" Command="{Binding NewInterimFile}"/>
                    </MenuItem>
                </Menu>
            </StackPanel>
        </Grid>

        <Grid Grid.Row="1" Margin="0,0,0,0">
            <ContentControl Content="{Binding CurrentViewModelTop}"/>
        </Grid>

        <Grid Grid.Row="2"  Visibility="Collapsed" Margin="0,0,0,0">
            <ContentControl Content="{Binding CurrentViewModelBottom}"/>
        </Grid>

    </Grid>
</Window>