InkForge/app/InkForge.Desktop/Views/MainWindow.axaml

<Window xmlns="https://github.com/avaloniaui"
        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="using:InkForge.Desktop.Views"
        mc:Ignorable="d"
        Width="800"
        Height="450"
        x:Class="InkForge.Desktop.Views.MainWindow"
        Title="MainWindow">
  <NativeMenu.Menu>
    <NativeMenu />
  </NativeMenu.Menu>

  <DockPanel>
    <NativeMenuBar DockPanel.Dock="Top" />

    <SplitView IsPaneOpen="true"
               DisplayMode="Inline">
      <SplitView.Pane>
        <local:WorkspacesView />
      </SplitView.Pane>

      <local:DocumentsView />
    </SplitView>
  </DockPanel>
</Window>