NullReferenceException in LayoutAnchorableFloatingWindowControl.OnInitialized

[meyerrn]

Hello,
I migrated from 3.3 to 3.5, but now the application does not start anymore. Crash while loading (Deserialize) a layout. See Stack trace below. "_model" is null. I think initialization is missing in constructor LayoutAnchorableFloatingWindowControl( LayoutAnchorableFloatingWindow model)

I skipped 3.4 because of another serious error.

System.NullReferenceException
HResult=0x80004003
Message=Object reference not set to an instance of an object.
Source=Xceed.Wpf.AvalonDock
StackTrace:
at Xceed.Wpf.AvalonDock.Controls.LayoutAnchorableFloatingWindowControl.OnInitialized(EventArgs e)
at System.Windows.FrameworkElement.TryFireInitialized()
at System.Windows.FrameworkElement.OnPropertyChanged(DependencyPropertyChangedEventArgs e)
at System.Windows.DependencyObject.NotifyPropertyChange(DependencyPropertyChangedEventArgs args)
at System.Windows.DependencyObject.UpdateEffectiveValue(EntryIndex entryIndex, DependencyProperty dp, PropertyMetadata metadata, EffectiveValueEntry oldEntry, EffectiveValueEntry& newEntry, Boolean coerceWithDeferredReference, Boolean coerceWithCurrentValue, OperationType operationType)
at System.Windows.DependencyObject.SetValueCommon(DependencyProperty dp, Object value, PropertyMetadata metadata, Boolean coerceWithDeferredReference, Boolean coerceWithCurrentValue, OperationType operationType, Boolean isInternal)
at System.Windows.PresentationSource.RootChanged(Visual oldRoot, Visual newRoot)
at System.Windows.Interop.HwndSource.set_RootVisualInternal(Visual value)
at System.Windows.Window.SetRootVisual()
at System.Windows.Window.SetRootVisualAndUpdateSTC()
at System.Windows.Window.SetupInitialState(Double requestedTop, Double requestedLeft, Double requestedWidth, Double requestedHeight)
at System.Windows.Window.CreateSourceWindow(Boolean duringShow)
at System.Windows.Window.ShowHelper(Object booleanBox)
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)
at System.Windows.Threading.DispatcherOperation.InvokeImpl()
at MS.Internal.CulturePreservingExecutionContext.CallbackWrapper(Object obj)
at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
at MS.Internal.CulturePreservingExecutionContext.Run(CulturePreservingExecutionContext executionContext, ContextCallback callback, Object state)
at System.Windows.Threading.DispatcherOperation.Invoke()
at System.Windows.Threading.Dispatcher.ProcessQueue()
at System.Windows.Threading.Dispatcher.WndProcHook(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)
at System.Windows.Threading.Dispatcher.LegacyInvokeImpl(DispatcherPriority priority, TimeSpan timeout, Delegate method, Object args, Int32 numArgs)
at MS.Win32.HwndSubclass.SubclassWndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam)
at MS.Win32.UnsafeNativeMethods.DispatchMessage(MSG& msg)
at System.Windows.Threading.Dispatcher.PushFrameImpl(DispatcherFrame frame)
at System.Windows.Application.RunDispatcher(Object ignore)
at System.Windows.Application.RunInternal(Window window)
at MyApp.App.Main()

[jmtuset]

I found the same problem.

I make a litlle change in the constructor to hotfix. Change base -> this

internal LayoutDocumentFloatingWindowControl( LayoutDocumentFloatingWindow model )
:this( model, false )
{
}

[Dirkster99]

It turns out that version 3.5 has the same critical issue in 2 different classes. The issue with the NullReference Exception shows when

• saving a layout with a floating tool window (NullReference Exception in LayoutAnchorableFloatingWindowControl) OR
• saving a layout with a floating document (NullReference Exception in LayoutDocumentFloatingWindowControl)

The correct fixes (see both references above) contain more than just setting the _model field since you are otherwise reloading a tool window layout without the abbility to close it later on (since the CloseCommand is not initialized if any of the fixes suggest here or there is applied).

[guy-avery]

@Dirkster99 - I think your statement is correct,

The correct fixes (see both references above) contain more than just setting the _model field since you are otherwise reloading a tool window layout without the abbility to close it later on (since the CloseCommand is not initialized if any of the fixes suggest here or there is applied).

But @jmtuset has the correct solution - you just need to call the other constructor - which will re-use the required initialisation code. Copying the same code between constructors in the same class is not good practice and usually indicates something is wrong with the design.

Hopefully the correct solution will be adopted but unless you have a very good reason not to, I would recommend you update your solution to represent @jmtuset's solution.

[Dirkster99]

@guy-avery Thanks for pointing this out to me. You are right. The issue is in both cases the same and it can be solved with the same resolution as suggested by @jmtuset I've commit the correct solution and will it roll out to NuGet/Release Version with the next bug fix :-)

[guy-avery]

@Dirkster99 - that's great - thanks for the response.

[XceedBoucherS]

Hi,
This is already fixed in v3.6 (the next community edition to be released).
You can already try the latest v3.8 version for free for 45 days here : https://xceed.com/xceed-toolkit-plus-for-wpf/

[junrau]

Since this is a significant issue, can you re-list 3.4 on NuGet, so we can revert until the fixed code is released?

[sa-he]

Can't you please just create a release 3.5.1 or something, that includes this bugfix?

[Dirkster99]

I have created a version with a fix (and now you know why): https://github.com/Dirkster99/AvalonDock

[sa-he]

Great @Dirkster99 , do you also publish nuget packages for your repo?