FileTreeView.axaml

<reactiveUi:ReactiveUserControl x:TypeArguments="basic:IFileTreeViewModel"
                                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:reactiveUi="http://reactiveui.net"
                                xmlns:basic="clr-namespace:Examples.TreeDataGrid.Basic"
                                mc:Ignorable="d" d:DesignWidth="800" d:DesignHeight="450"
                                x:Class="Examples.TreeDataGrid.Basic.FileTreeView">
    <Design.DataContext>
        <basic:FileTreeDesignViewModel />
    </Design.DataContext>

    <!-- Visual Tree -->
    <TreeDataGrid Classes="TreeWhiteCaret" ShowColumnHeaders="True"
                  x:Name="ModFilesTreeDataGrid" Width="1"/>

</reactiveUi:ReactiveUserControl>