<view:CustomTabControl ItemsSource="{Binding OpenTabs}" Grid.Column="1" x:Name="Tabs">
    <view:CustomTabControl.Resources>
        <DataTemplate DataType="{x:Type model:Tennant}">
            <ScrollViewer>
                <Grid>
                    <TextBlock Text="{Binding name}"/>
                </Grid>
            </ScrollViewer>
        </DataTemplate>
        <DataTemplate DataType="{x:Type model:Property}">
            <ScrollViewer>
                <Grid MinWidth="350">
                    <!-- All of the stuff that works for the Property layout in here -->
                </Grid>
            </ScrollViewer>
        </DataTemplate>
    </view:CustomTabControl.Resources>
</view:CustomTabControl>

<ScrollViewer VerticalScrollBarVisibility="Auto">
    <StackPanel>
        <TextBlock Margin="10,5" Text="Properties" FontSize="16"/>
        <ListBox x:Name="propertiesList" ItemsSource="{Binding Properties, Mode=TwoWay}">
            <ListBox.ItemTemplate>
                <DataTemplate DataType="{x:Type model:Property}">
                    <TextBlock Text="{Binding title}"/>
                </DataTemplate>
            </ListBox.ItemTemplate>
        </ListBox>
        <TextBlock Margin="10,5" Text="Tennants" FontSize="16"/>
        <ListBox x:Name="tennantsList" ItemsSource="{Binding Tennants, Mode=TwoWay}">
            <ListBox.ItemTemplate>
                <DataTemplate DataType="{x:Type model:Tennant}">
                    <TextBlock Text="{Binding name}"/>
                </DataTemplate>
            </ListBox.ItemTemplate>
        </ListBox>
    </StackPanel>
</ScrollViewer>

[Serializable]
public class Tennant : ISerializable, INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;

    private bool current;
    private string name;
    private string phone;
    private string email;
    private string occupation;
    public bool Current { get { return current; } set { current = value; OnPropertyChanged("Current"); } }
    public string Name { get { return name; } set { name = value; OnPropertyChanged("Name"); } }
    public string Phone { get { return phone; } set { phone = value; OnPropertyChanged("Phone"); } }
    public string Email { get { return email; } set { email = value; OnPropertyChanged("Email"); } }
    public string Occupation { get { return occupation; } set { occupation = value; OnPropertyChanged("Occupation"); } }

    public Tennant()
    {

    }

    public Tennant(bool current, string name, string phone, string email, string occupation)
    {
        this.Current = current;
        this.Name = name;
        this.Phone = phone;
        this.Email = email;
        this.Occupation = occupation;
    }

    private void OnPropertyChanged(string p)
    {
        if (PropertyChanged != null)
        {
            PropertyChanged(this, new PropertyChangedEventArgs(p));
        }
    }

    public override string ToString()
    {
        return "" + Current + " " + Name + " " + Phone + " " + Email + " " + Occupation;
    }

    public Tennant(SerializationInfo info, StreamingContext context)
    {
        this.Current = (bool)info.GetValue("Current", typeof(bool));
        this.Name = (string)info.GetValue("Name", typeof(string));
        this.Phone = (string)info.GetValue("Phone", typeof(string));
        this.Email = (string)info.GetValue("Email", typeof(string));
        this.Occupation = (string)info.GetValue("Occupation", typeof(string));

    }

    public void GetObjectData(SerializationInfo info, StreamingContext context)
    {
        info.AddValue("Current", this.Current);
        info.AddValue("Name", this.Name);
        info.AddValue("Phone", this.Phone);
        info.AddValue("Email", this.Email);
        info.AddValue("Occupation", this.Occupation);
    }
}

public class Property : ISerializable
{
    public string address { get; set; }
    public string city { get; set; }
    public string postcode { get; set; }
    // ...

    public Property()
    {
        // ...
    }

    public string toString()
    {
        return title;
    }

    public bool hasPhotos()
    {
        return false;
    }

    public bool hasTennant()
    {
        return false;
    }

    public void addTennant(Tennant tennant)
    {
        tennants.Add(tennant);
    }

    public void addPhoto(Photo photo)
    {
        photos.Add(photo);
    }

    public void addIssue(Problem issue)
    {
        issues.Add(issue);
    }

    public Property(SerializationInfo info, StreamingContext context)
    {
        // ...
    }
    public void GetObjectData(SerializationInfo info, StreamingContext context)
    {
        // ...
    }
}

// Inside the Constructor
OpenTabs = new ObservableCollection<Object>();
EventManager.RegisterClassHandler(typeof(ListBoxItem),
    ListBoxItem.MouseLeftButtonDownEvent,
    new RoutedEventHandler(this.OnMouseLeftButtonDown));

private void OnMouseLeftButtonDown(object sender, RoutedEventArgs e)
{
    ListBoxItem selected = sender as ListBoxItem;
    try
    {
        string t = (selected.Content as Property).title;
        Property cur = selected.Content as Property;
        OpenProperty(cur);
    }
    catch (NullReferenceException nre)
    {
        Tennant cur = selected.Content as Tennant;
        OpenTennant(cur);
    }
}

// This method opens a new tab with a Property's details in it
private void OpenProperty(Property property)
{
    this.HomeView.Visibility = System.Windows.Visibility.Hidden;
    this.TabbedView.Visibility = System.Windows.Visibility.Visible;
    MainWindow.OpenTabs.Add(property);
    this.Tabs.SelectedIndex = MainWindow.OpenTabs.IndexOf(property);
}

// This method opens a new tab with a Tennant's details in it
private void OpenTennant(Tennant tennant)
{
    this.HomeView.Visibility = System.Windows.Visibility.Hidden;
    this.TabbedView.Visibility = System.Windows.Visibility.Visible;
    MainWindow.OpenTabs.Add(tennant);
    this.Tabs.SelectedIndex = MainWindow.OpenTabs.IndexOf(tennant);
}