I want to build a UserInterface like this (a timeline for a video editor)

and I have all classes:
public class Timeline
{
public Timeline()
{
groups = new ObservableCollection<Group>();
}
public ObservableCollection<Group> groups { get; set; }
}
public class Group
{
public string Name { get; set; }
public TrackGroup()
{
tracks = new List<Track>();
}
public List<Track> tracks { get; set; }
}
public class Track
{
public Track()
{
units= new ObservableCollection<Unit>();
}
public ObservableCollection<Unit> units { get; set; }
}
public class Unit
{
public string unitName { get; set; }
}
And in Main I have this:
public Timeline timeline = new Timeline();
public Unit unit = new Unit();
public Track track = new Track();
public Group group = new Group();
track.units.Add(unit);
group.tracks.Add(track);
timeline.groups.Add(group);
And in Main.xaml(not complete because it doesn't work)
<ListBox
HorizontalContentAlignment="Stretch"
ItemsSource="{Binding timeline.groups}">
<ListBox.ItemTemplate>
<DataTemplate>
<DockPanel LastChildFill="True">
<ItemsControl ItemsSource="{Binding timeline.groups.tracks}">
<ItemsControl.ItemTemplate >
<ItemsControl ItemsSource="{Binding timeline.groups.tracks.units}">
<ItemsControl.ItemTemplate >
</ItemsControl.ItemTemplate >
</ItemsControl>
</ItemsControl.ItemTemplate>
</ItemsControl>
</DockPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
How can I binding each itemssource? because timeline, group, track all are list, so I need to show them in ItemsControl. I was very confused