Steps to replicate:
Take any standard Syncfusion example which uses DockingManager, e.g. DockingDemo_2008. Put diagram control into the ContentControl.
syncfusion:DockingManager.Header="Docking"
syncfusion:DockingManager.State="Document"
syncfusion:DockingManager.CanDock="False"
syncfusion:DocumentContainer.MDIBounds="60,60,300,300"
syncfusion:DockingManager.CanFloat="False"
>
*** Any time you drag anything from SymbolPalette onto the diagram, you're getting this exception ****
"Object reference not set to an instance of an object."
at Syncfusion.Windows.Tools.Controls.DocumentTabControl.UpdateMenuItems(TabItemExt tabItem)
at Syncfusion.Windows.Tools.Controls.DragDropHelper.DropTarget_PreviewDrop(Object sender, DragEventArgs e)
at System.Windows.DragEventArgs.InvokeEventHandler(Delegate genericHandler, Object genericTarget)
at System.Windows.RoutedEventArgs.InvokeHandler(Delegate handler, Object target)
at System.Windows.RoutedEventHandlerInfo.InvokeHandler(Object target, RoutedEventArgs routedEventArgs)
at System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised)
at System.Windows.UIElement.RaiseEventImpl(DependencyObject sender, RoutedEventArgs args)
at System.Windows.UIElement.RaiseEvent(RoutedEventArgs e)
at System.Windows.OleDropTarget.RaiseDragEvent(RoutedEvent dragEvent, Int32 dragDropKeyStates, Int32& effects, DependencyObject target, Point targetPoint)
at System.Windows.OleDropTarget.MS.Win32.UnsafeNativeMethods.IOleDropTarget.OleDrop(Object data, Int32 dragDropKeyStates, Int64 point, Int32& effects)
at MS.Win32.UnsafeNativeMethods.DoDragDrop(IDataObject dataObject, IOleDropSource dropSource, Int32 allowedEffects, Int32[] finalEffect)
at System.Windows.OleServicesContext.OleDoDragDrop(IDataObject dataObject, IOleDropSource dropSource, Int32 allowedEffects, Int32[] finalEffect)
at System.Windows.DragDrop.OleDoDragDrop(DependencyObject dragSource, DataObject dataObject, DragDropEffects allowedEffects)
at System.Windows.DragDrop.DoDragDrop(DependencyObject dragSource, Object data, DragDropEffects allowedEffects)
at Syncfusion.Windows.Diagram.SymbolPaletteItem.OnMouseMove(MouseEventArgs e)
at System.Windows.UIElement.OnMouseMoveThunk(Object sender, MouseEventArgs e)
at System.Windows.Input.MouseEventArgs.InvokeEventHandler(Delegate genericHandler, Object genericTarget)
at System.Windows.RoutedEventArgs.InvokeHandler(Delegate handler, Object target)
at System.Windows.RoutedEventHandlerInfo.InvokeHandler(Object target, RoutedEventArgs routedEventArgs)
at System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised)
at System.Windows.UIElement.RaiseEventImpl(DependencyObject sender, RoutedEventArgs args)
at System.Windows.UIElement.RaiseEvent(RoutedEventArgs args, Boolean trusted)
at System.Windows.Input.InputManager.ProcessStagingArea()
at System.Windows.Input.InputManager.ProcessInput(InputEventArgs input)
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, Int32 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, Boolean isSingleParameter)
at System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Boolean isSingleParameter, Delegate catchHandler)
at System.Windows.Threading.Dispatcher.WrappedInvoke(Delegate callback, Object args, Boolean isSingleParameter, Delegate catchHandler)
at System.Windows.Threading.Dispatcher.InvokeImpl(DispatcherPriority priority, TimeSpan timeout, Delegate method, Object args, Boolean isSingleParameter)
at System.Windows.Threading.Dispatcher.Invoke(DispatcherPriority priority, Delegate method, Object arg)
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.Threading.Dispatcher.PushFrame(DispatcherFrame frame)
at System.Windows.Threading.Dispatcher.Run()
at System.Windows.Application.RunDispatcher(Object ignore)
at System.Windows.Application.RunInternal(Window window)
at System.Windows.Application.Run(Window window)
at System.Windows.Application.Run()
at DockingStudio.App.Main() in C:\Documents and Settings\kevina\My Documents\syncfusion\essentialstudio\7.2.0.20\WPF\Tools.WPF\Samples\3.5\WindowsSamples\Docking\Docking Demo\CS\obj\Debug\App.g.cs:line 0
at System.AppDomain._nExecuteAssembly(Assembly assembly, String[] args)
at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
at System.Threading.ThreadHelper.ThreadStart()