NullReferenceException-after-minimizing-Strategy-window

Hi,

I keep finding this exception:

CODE:
System.NullReferenceException: Object reference not set to an instance of an object.
   at WealthLab.WPF.MDIChild.set_WindowState(WindowState value)
   at WealthLab.WPF.MDIContainer.set_TopmostWindow(MDIChild value)
   at WealthLab.WPF.MDIContainer.BringToTop(MDIChild child)
   at WealthLab.WPF.MDIChild.PrepareCandidate(Object init, MouseButtonEventArgs connection)
   at System.Windows.RoutedEventArgs.InvokeHandler(Delegate handler, Object target)
   at System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised)
   at System.Windows.UIElement.ReRaiseEventAs(DependencyObject sender, RoutedEventArgs args, RoutedEvent newEvent)
   at System.Windows.RoutedEventArgs.InvokeHandler(Delegate handler, Object target)
   at System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised)
   at System.Windows.UIElement.RaiseEventImpl(DependencyObject sender, RoutedEventArgs args)
   at System.Windows.UIElement.RaiseTrustedEvent(RoutedEventArgs args)
   at System.Windows.Input.InputManager.ProcessStagingArea()
   at System.Windows.Input.InputProviderSite.ReportInput(InputReport inputReport)
   at System.Windows.Interop.HwndMouseInputProvider.ReportInput(IntPtr hwnd, InputMode mode, Int32 timestamp, RawMouseActions actions, Int32 x, Int32 y, Int32 wheel)
   at System.Windows.Interop.HwndMouseInputProvider.FilterMessage(IntPtr hwnd, WindowMessage msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
   at System.Windows.Interop.HwndSource.InputFilterMessage(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
   at MS.Win32.HwndWrapper.WndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
   at MS.Win32.HwndSubclass.DispatcherCallbackOperation(Object o)
   at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs)
   at System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Int32 numArgs, Delegate catchHandler)

This usually happens with strategies that I find with the Strategy Evolver: eventually I click to open and better analyse some strategy; then I minimize the window, with the Strategy Evolver still running; eventually, this exception then happens a while after maximizing the strategy again (not in a deterministic way, as far as I can see): no matter where I click, it just keeps popping and I am not even able to save the strategy for safekeeping.

I am running a fresh installation with all latest updates; and only the WL extensions, no third party ones, at this point. Unfortunately, I still didn't find a proper way of reproducing it: it keeps happening, but seems to be random... When it does happen, the only way to continue seems to be shutting down WL8.