Hi Pavel,
I ran your application on my machine as is. It runs without problems. When opening the mainWindow XAML file in the XAML designer I got the same errors I describe in my original post (See attachment).
However, immediately after running your example, I opened my application (without anything else changed) and my mainWindow and its RibbonView display correctly in the XAML designer.
I rebooted my machine and duplicated the steps above several times with the same results. The mainWindow of your sample application does not display on the designer while my mainWindow does.
Please note that error in the designer is always repeated 3 times see below
Thanks for you help
Philippe
XAML Designer Error triggered by your sample app on my machine
System.ArgumentException
'{DependencyProperty.UnsetValue}' is not a valid value for the 'Telerik.Windows.Controls.RadRibbonGallery.Icon' property on a Setter.
at Microsoft.Expression.DesignHost.Isolation.Remoting.STAMarshaler.WaitForCompletion(NestedCallContext nestedCallContext, BlockingCall call, WaitHandle timeoutSignal) at Microsoft.Expression.DesignHost.Isolation.Remoting.STAMarshaler.MarshalOutSynchronous(Action action, Int32 targetApartmentId, WaitHandle aborted, WaitHandle timeoutSignal) at Microsoft.Expression.DesignHost.Isolation.Remoting.STAMarshaler.MarshalOut(Action action, Int32 targetApartmentId, WaitHandle aborted, CallSynchronizationMode syncMode, WaitHandle timeoutSignal) at Microsoft.Expression.DesignHost.Isolation.Remoting.ThreadMarshaler.MarshalOut[TValue](RemoteHandle`1 targetObject, Action action, CallSynchronizationMode syncMode) at Microsoft.Expression.DesignHost.Isolation.Remoting.ThreadMarshaler.MarshalOut[TResult,TValue](RemoteHandle`1 targetObject, Func`2 func, CallSynchronizationMode syncMode) at Microsoft.Expression.DesignHost.Isolation.Remoting.LocalDesignerService.CreateDesignerImpl(IHostSourceItem item, IHostTextEditor editor, RemoteCancellationToken remoteCancelToken) at Microsoft.Expression.DesignHost.Isolation.Remoting.LocalDesignerService.<>c__DisplayClass12.<Microsoft.Expression.DesignHost.IDesignerService.CreateDesigner>b__11(RemoteCancellationToken remoteToken) at Microsoft.Expression.DesignHost.Isolation.Remoting.LocalDesignerService.CallWithCancellation[TResult](CancellationToken cancelToken, Func`2 func) at Microsoft.Expression.DesignHost.Isolation.Remoting.LocalDesignerService.Microsoft.Expression.DesignHost.IDesignerService.CreateDesigner(IHostSourceItem item, IHostTextEditor editor, CancellationToken cancelToken) at Microsoft.Expression.DesignHost.IsolatedDesignerService.IsolatedDesignerView.CreateDesignerViewInfo(CancellationToken cancelToken)
System.ArgumentException
'{DependencyProperty.UnsetValue}' is not a valid value for the 'Telerik.Windows.Controls.RadRibbonGallery.Icon' property on a Setter.
Server stack trace: at Microsoft.Expression.DesignHost.Isolation.Remoting.STAMarshaler.WaitForCompletion(NestedCallContext nestedCallContext, BlockingCall call, WaitHandle timeoutSignal) at Microsoft.Expression.DesignHost.Isolation.Remoting.STAMarshaler.MarshalIn(Action action, Int32 targetApartmentId) at Microsoft.Expression.DesignHost.Isolation.Remoting.ThreadMarshaler.MarshalIn(IRemoteObject targetObject, Action action) at Microsoft.Expression.DesignHost.Isolation.Remoting.ThreadMarshaler.MarshalIn[TResult](IRemoteObject targetObject, Func`1 func) at Microsoft.Expression.DesignHost.Isolation.Remoting.RemoteDesignerService.Microsoft.Expression.DesignHost.Isolation.Remoting.IRemoteDesignerService.CreateDesigner(IRemoteHostSourceItem remoteItem, IRemoteHostTextEditor remoteEditor, IRemoteCancellationToken remoteToken) at System.Runtime.Remoting.Messaging.StackBuilderSink._PrivateProcessMessage(IntPtr md, Object[] args, Object server, Object[]& outArgs) at System.Runtime.Remoting.Messaging.StackBuilderSink.SyncProcessMessage(IMessage msg)Exception rethrown at [0]: at System.Runtime.Remoting.Proxies.RealProxy.HandleReturnMessage(IMessage reqMsg, IMessage retMsg) at System.Runtime.Remoting.Proxies.RealProxy.PrivateInvoke(MessageData& msgData, Int32 type) at Microsoft.Expression.DesignHost.Isolation.Remoting.IRemoteDesignerService.CreateDesigner(IRemoteHostSourceItem remoteItem, IRemoteHostTextEditor remoteEditor, IRemoteCancellationToken cancelToken) at Microsoft.Expression.DesignHost.Isolation.Remoting.LocalDesignerService.<>c__DisplayClass8.<CreateDesignerImpl>b__6(IRemoteDesignerService d) at Microsoft.Expression.DesignHost.Isolation.Remoting.ThreadMarshaler.<>c__DisplayClass4`2.<MarshalOut>b__3() at Microsoft.Expression.DesignHost.Isolation.Remoting.STAMarshaler.Call.InvokeWorker()
System.ArgumentException
'{DependencyProperty.UnsetValue}' is not a valid value for the 'Telerik.Windows.Controls.RadRibbonGallery.Icon' property on a Setter.
at System.Windows.Setter.Seal() at System.Windows.SetterBaseCollection.Seal() at System.Windows.Style.Seal() at System.Windows.Style.System.Windows.ISealable.Seal() at System.Windows.StyleHelper.SealIfSealable(Object value) at System.Windows.ResourceDictionary.SealValue(Object value) at System.Windows.ResourceDictionary.SealValues() at System.Windows.ResourceDictionary.AddOwner(DispatcherObject owner) at System.Windows.ResourceDictionary.PropagateParentOwners(ResourceDictionary mergedDictionary) at System.Windows.ResourceDictionary.OnMergedDictionariesChanged(Object sender, NotifyCollectionChangedEventArgs e) at System.Collections.ObjectModel.ObservableCollection`1.OnCollectionChanged(NotifyCollectionChangedEventArgs e) at System.Collections.ObjectModel.ObservableCollection`1.InsertItem(Int32 index, T item) at System.Windows.ResourceDictionaryCollection.InsertItem(Int32 index, ResourceDictionary item) at System.Collections.ObjectModel.Collection`1.Add(T item) at Microsoft.Expression.DesignSurface.View.WPFSceneView.WpfResourceHost.TrySetApplicationResources() at Microsoft.Expression.DesignSurface.View.WPFSceneView.WpfResourceHost.EndInstanceBuilding() at Microsoft.Expression.DesignSurface.View.WPFSceneView.CrossDocumentUpdateToken.System.IDisposable.Dispose() at Microsoft.Expression.Platform.InstanceBuilders.ViewNodeManager.UpdateInstances(IAttachViewRoot siteRoot, IList`1 contextNodes, CancellationToken cancelToken) at Microsoft.Expression.DesignSurface.View.XamlSceneView.UpdateInstancesInternal() at Microsoft.Expression.DesignSurface.View.XamlSceneView.UpdateInternal(Boolean updateInstances, Boolean updateReferences) at Microsoft.Expression.DesignSurface.View.WPFSceneView.UpdateInternal(Boolean updateInstances, Boolean updateReferences) at Microsoft.Expression.DesignSurface.View.XamlSceneView.Update(Boolean updateReferences) at Microsoft.Expression.DesignSurface.View.ViewUpdateManager.UpdateInvalidRelatedDocuments(SceneView view) at Microsoft.Expression.DesignSurface.View.XamlSceneView.EnsureActiveViewUpdated() at Microsoft.Expression.DesignSurface.View.WPFSceneView.EnsureActiveViewUpdated() at Microsoft.Expression.DesignSurface.View.XamlSceneView.SetVisible(Boolean visible) at Microsoft.Expression.DesignSurface.View.WPFSceneView.SetVisible(Boolean visible) at Microsoft.Expression.DesignSurface.DocumentViewContext.CreateAndOpenView(ISourceItemContext sourceItem, CancellationToken cancelToken, Boolean activate, Boolean ensureOpenInHost, Boolean suppressUI) at Microsoft.Expression.DesignSurface.DesignerService.CreateDesigner(IHostSourceItem item, IHostTextEditor editor, CancellationToken cancelToken) at Microsoft.Expression.DesignHost.Isolation.Remoting.RemoteDesignerService.<>c__DisplayClass10.<>c__DisplayClass12.<Microsoft.Expression.DesignHost.Isolation.Remoting.IRemoteDesignerService.CreateDesigner>b__f(CancellationToken cancelToken) at Microsoft.Expression.DesignHost.Isolation.Remoting.RemoteDesignerService.CallWithCancellation[TResult](IRemoteCancellationToken remoteToken, Func`2 func) at Microsoft.Expression.DesignHost.Isolation.Remoting.RemoteDesignerService.<>c__DisplayClass10.<Microsoft.Expression.DesignHost.Isolation.Remoting.IRemoteDesignerService.CreateDesigner>b__e() at Microsoft.Expression.DesignHost.Isolation.Remoting.ThreadMarshaler.<>c__DisplayClass16`1.<MarshalIn>b__15() at Microsoft.Expression.DesignHost.Isolation.Remoting.STAMarshaler.Call.InvokeWorker()