MercuryConverter/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="clr-namespace:MercuryConverter"
        mc:Ignorable="d" d:DesignWidth="800" d:DesignHeight="450"

        x:Class="MercuryConverter.MainWindow"
        Title="MercuryConverter"
        Width="1024" Height="800"
        MinWidth="800" MinHeight="600"
        ExtendClientAreaToDecorationsHint="True"
>
    <!-- Components -->
    <Panel>
        <!-- Banner -->
        <StackPanel>
            <UserControl Background="{DynamicResource SystemAltHighColor}" Height="86"/>
        </StackPanel>
        <StackPanel HorizontalAlignment="Right">
            <Image Height="86" Source="{DynamicResource BannerBitmap}"/>
        </StackPanel>

        <DockPanel>
            
            <Menu Name="MenuBar" DockPanel.Dock="Top">
                <MenuItem Header="File">
                    <MenuItem Header="Open Data Folder..." />
                </MenuItem>
            </Menu>

            <TabControl>
                <TabItem Header="selection">
                    <UserControl Name="SelectionControl"/>
                </TabItem>

                <TabItem Header="export">
                </TabItem>
            </TabControl>
        </DockPanel>
    </Panel>
</Window>