Hello,

The observed behavior is consider as an expected one. When the Docking controls is unloaded  internally in our implementation all the ToolWindows are closed. Because of that when the layout gets saved all ToolWindows are already closed and are saved as such. So, when the layout is loaded no ToolWindows should be visible including the FloatingOnly ToolWindow. The visualization of the FloatingOnly ToolWindow we consider as a bug and will be fixed with one of our next internal builds.

If you need however, to save the layout when the Docking is unloaded and before the ToolWindows are closed from our internal logic you need to handle the event as follows:

public MainWindow()
{
    InitializeComponent();
	EventManager.RegisterClassHandler(typeof(RadDocking), RadDocking.UnloadedEvent, new RoutedEventHandler(OnUnloaded));
}

private void OnUnloaded(object sender, RoutedEventArgs e)
{
	//save the layout here		
}

Regards, 
Nasko