DocumentWindow and Binding to Collection

                   <docking:Workspace>
                        <docking:TabbedMdiHost>
                            <docking:TabbedMdiContainer x:Name="_documentContainer" ItemsSource="{Binding}">
                            </docking:TabbedMdiContainer>
                        </docking:TabbedMdiHost>
                    </docking:Workspace>

ObservableCollection<DocumentWindow> _documentRoot

:
:
:
_documentContainer.ItemsSource = _documentRoot;

DocumentWindow newDocument = new DocumentWindow();
newDocument.Title = assetName;
newDocument.Content = newDesigner;
newDocument.Focusable = true;
newDocument.IsEnabled = true;

_documentRoot.Add(newDocument);