How to find out whether the Tool is Docked as a Document? #307

public void AfterInsertAnchorable(LayoutRoot layout, LayoutAnchorable anchorableShown)
        {
            // If this is the first anchorable added to this pane, then use the preferred size.
            var tool = anchorableShown.Content as ITool;
            if (tool != null)
            {
                var anchorablePane = anchorableShown.Parent as LayoutAnchorablePane;
                if (anchorablePane != null && anchorablePane.ChildrenCount == 1)
                {
                    switch (tool.PreferredLocation)
                    {
                        case PaneLocation.Left:
                        case PaneLocation.Right:
                            anchorablePane.DockWidth = new GridLength(tool.PreferredWidth, GridUnitType.Pixel);
                            break;
                        case PaneLocation.Bottom:
                            anchorablePane.DockHeight = new GridLength(tool.PreferredHeight, GridUnitType.Pixel);
                            break;
                        case PaneLocation.Floating:
                            {
                                anchorableShown.FloatingHeight = tool.PreferredHeight;
                                anchorableShown.FloatingWidth = tool.PreferredWidth;

                                var window = Application.Current.MainWindow;
                                var screen = System.Windows.Forms.Screen.FromHandle(new WindowInteropHelper(window).Handle);
                                anchorableShown.FloatingTop = (screen.WorkingArea.Height / 2d) - (anchorableShown.FloatingHeight / 2d);
                                anchorableShown.FloatingLeft = (screen.WorkingArea.Width / 2d) - (anchorableShown.FloatingWidth / 2d);
                                anchorableShown.Float();
                                break;
                            }
                        case PaneLocation.Document:
                            anchorableShown.DockAsDocument();
                            break;
                        default:
                            throw new ArgumentOutOfRangeException();
                    }
                }
            }
        }