Questions

I have 2 charts in my application. They work fine until I add an event to the chart (xaml). The Designer gives an Unhandled Exception with the following details

System.ArgumentException
An item with the same key has already been added.
at System.ThrowHelper.ThrowArgumentException(ExceptionResource resource)
at System.Collections.Generic.Dictionary2.Insert(TKey key, TValue value, Boolean add)
at Microsoft.Expression.DesignModel.Metadata.MemberCollection.get_FieldIndex()
at Microsoft.Expression.DesignModel.Metadata.MemberCollection.CreateField(String fieldName, MemberKey& key)
at Microsoft.Expression.DesignModel.Metadata.MemberCollection.CreateMember(MemberType memberTypes, String memberName, MemberKey& key)
at Microsoft.Expression.DesignModel.Metadata.MemberCollection.TryGetCachedMember(MemberType memberTypes, String memberName, Boolean create, IMember& member)
at Microsoft.Expression.DesignModel.Metadata.MemberCollection.GetMember(MemberType memberTypes, String memberName, MemberAccessTypes access)
at Microsoft.Expression.DesignModel.Metadata.ProjectContextType.GetMember(MemberType memberTypes, String memberName, MemberAccessTypes access)
at Microsoft.Expression.Markup.XamlTypeHelper.GetPropertyKey(XamlParserContext parserContext, ITextLocation lineInformation, XmlNamespace xmlNamespace, String typeAndPropertyName, XmlNamespace targetTypeNamespace, IType targetTypeId, MemberType memberTypes, MemberType defaultType, Boolean allowProtectedPropertiesOnTargetType)
at Microsoft.Expression.Markup.XamlParser.GetPropertyKey(XamlParserContext parserContext, XmlElementReference xmlElementReference, XmlElement xmlElement, XmlAttribute attribute, IType targetType, Boolean allowProtectedPropertiesOnTargetType, IProperty& propertyKey)
at Microsoft.Expression.Markup.XamlParser.AddPropertiesAndChildren(XamlParserContext parserContext, DocumentCompositeNodeReference nodeReference, XmlElementReference xmlElementReference, XmlElement xmlElement, Predicate1 propertyFilter)
at Microsoft.Expression.Markup.XamlParser.AddPropertiesAndChildren(XamlParserContext parserContext, DocumentCompositeNodeReference nodeReference, XmlElementReference xmlElementReference, XmlElement xmlElement)
at Microsoft.Expression.Markup.XamlParser.ParseCompositeElement(XamlParserContext parserContext, IDocumentNodeReference nodeReference, IType typeId, XmlElementReference xmlElementReference, XmlElement xmlElement)
at Microsoft.Expression.Markup.XamlParser.ParseElementContent(XamlParserContext parserContext, IDocumentNodeReference nodeReference, IType typeId, XmlElementReference xmlElementReference, XmlElement xmlElement)
at Microsoft.Expression.Markup.XamlParser.ParseElement(XamlParserContext parserContext, IDocumentNodeReference nodeReference, XmlElementReference xmlElementReference, XmlElement xmlElement, DocumentNode& node)
at Microsoft.Expression.Markup.XamlParser.ParseRegion(IReadableSelectableTextBuffer textBuffer, DocumentNode parentNode, DocumentNode oldNode, ITextRange span, IList1& errors)
at Microsoft.Expression.Markup.XamlLanguageService.IncrementalParse(ITextChangesTracker textChanges, IList1 errorsAndWarnings, IList`1& newErrors)
at Microsoft.Expression.Markup.MarkupDocument.CommitTextEdits(Boolean forceUpdateIfWarnings)
at Microsoft.Expression.DesignSurface.View.SceneView.CommitTextEditsInternal(Boolean forceUpdateIfWarnings)
at Microsoft.Expression.DesignSurface.View.SceneView.SynchronizeTextEdits()
at Microsoft.Expression.DesignSurface.View.SceneView.StopTimerAndCommitTextEdits()
at Microsoft.Expression.DesignSurface.View.SceneView.TextCommitTimeoutTimer_Tick(Object sender, EventArgs e)
at System.Windows.Threading.DispatcherTimer.FireTick(Object unused)
at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs)
at MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen(Object source, Delegate method, Object args, Int32 numArgs, Delegate catchHandler)
at System.Windows.Threading.DispatcherOperation.InvokeImpl()
at System.Windows.Threading.DispatcherOperation.InvokeInSecurityContext(Object state)
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 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 MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen(Object source, Delegate method, 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.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 Microsoft.Expression.DesignHost.Isolation.DesignerProcess.RunApplication()
at Microsoft.Expression.DesignHost.Isolation.DesignerProcess.<>c__DisplayClass2.b__0()
at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
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 System.Threading.ThreadHelper.ThreadStart()

The Chart code is as below. If I remove the Preview mouse down and reload then it woks fine.

        <s:SciChartSurface x:Name="sciChartFull" s:ThemeManager.Theme="Chrome" Grid.Column="0" PreviewMouseDown="sciChartFull_PreviewMouseDown"  >
            <s:SciChartSurface.RenderableSeries>
                <s:FastLineRenderableSeries x:Name="lineSeriesFull" SeriesColor="#FFBB6464" />
                <s:XyScatterRenderableSeries x:Name="pointSeriesFull">
                    <s:XyScatterRenderableSeries.PointMarker>
                        <s:EllipsePointMarker Width="5" Height="5" Fill="#FF04571B" Stroke="#FF04571B" StrokeThickness="1"></s:EllipsePointMarker>
                    </s:XyScatterRenderableSeries.PointMarker>
                </s:XyScatterRenderableSeries>
            </s:SciChartSurface.RenderableSeries>
            <s:SciChartSurface.XAxis>
                <s:TimeSpanAxis DrawMajorGridLines="False" DrawMinorGridLines="False" />
            </s:SciChartSurface.XAxis>
            <s:SciChartSurface.YAxis>
                <s:NumericAxis DrawMajorGridLines="False" DrawMinorGridLines="False" Visibility="Collapsed"/>
            </s:SciChartSurface.YAxis>
        </s:SciChartSurface>