我有一个WPF应用程序，由于System.InvalidOperationException，在按下 Alt 或 Ctrl 键时会抛出DependencyProperty.UnsetValue。
堆栈跟踪和调试输出不提供任何提示导致异常的原因。这是堆栈跟踪：
WindowsBase.dll!System.Windows.DependencyObject.GetEffectiveValue(System.Windows.EntryIndex entryIndex, System.Windows.DependencyProperty dp, System.Windows.RequestFlags requests) Unknown
WindowsBase.dll!System.Windows.DependencyObject.GetValueEntry(System.Windows.EntryIndex entryIndex, System.Windows.DependencyProperty dp, System.Windows.PropertyMetadata metadata, System.Windows.RequestFlags requests) Unknown
WindowsBase.dll!System.Windows.DependencyObject.GetValue(System.Windows.DependencyProperty dp) Unknown
PresentationFramework.dll!System.Windows.FrameworkElement.FocusVisualStyle.get() Unknown
PresentationFramework.dll!System.Windows.Input.KeyboardNavigation.ShowFocusVisual(System.Windows.DependencyObject element) Unknown
PresentationFramework.dll!System.Windows.Input.KeyboardNavigation.ProcessInput(System.Windows.Input.InputEventArgs inputEventArgs) Unknown
PresentationCore.dll!System.Windows.Input.InputManager.RaiseProcessInputEventHandlers(System.Windows.Input.ProcessInputEventHandler postProcessInput, System.Windows.Input.ProcessInputEventArgs processInputEventArgs) Unknown
PresentationCore.dll!System.Windows.Input.InputManager.ProcessStagingArea() Unknown
PresentationCore.dll!System.Windows.Input.InputManager.ProcessInput(System.Windows.Input.InputEventArgs input) Unknown
PresentationCore.dll!System.Windows.Input.InputProviderSite.ReportInput(System.Windows.Input.InputReport inputReport) Unknown
PresentationCore.dll!System.Windows.Interop.HwndKeyboardInputProvider.ReportInput(System.IntPtr hwnd, System.Windows.Input.InputMode mode, int timestamp, System.Windows.Input.RawKeyboardActions actions, int scanCode, bool isExtendedKey, bool isSystemKey, int virtualKey) Unknown
PresentationCore.dll!System.Windows.Interop.HwndKeyboardInputProvider.ProcessKeyAction(ref System.Windows.Interop.MSG msg, ref bool handled) Unknown
PresentationCore.dll!System.Windows.Interop.HwndSource.CriticalTranslateAccelerator(ref System.Windows.Interop.MSG msg, System.Windows.Input.ModifierKeys modifiers) Unknown
PresentationCore.dll!System.Windows.Interop.HwndSource.OnPreprocessMessage(object param) Unknown
WindowsBase.dll!System.Windows.Threading.ExceptionWrapper.InternalRealCall(System.Delegate callback, object args, int numArgs) Unknown
WindowsBase.dll!System.Windows.Threading.ExceptionWrapper.TryCatchWhen(object source, System.Delegate callback, object args, int numArgs, System.Delegate catchHandler) Unknown
WindowsBase.dll!System.Windows.Threading.Dispatcher.LegacyInvokeImpl(System.Windows.Threading.DispatcherPriority priority, System.TimeSpan timeout, System.Delegate method, object args, int numArgs) Unknown
WindowsBase.dll!System.Windows.Threading.Dispatcher.Invoke(System.Windows.Threading.DispatcherPriority priority, System.Delegate method, object arg) Unknown
PresentationCore.dll!System.Windows.Interop.HwndSource.OnPreprocessMessageThunk(ref System.Windows.Interop.MSG msg, ref bool handled) Unknown
WindowsBase.dll!System.Windows.Interop.ComponentDispatcherThread.RaiseThreadMessage(ref System.Windows.Interop.MSG msg) Unknown
WindowsBase.dll!System.Windows.Threading.Dispatcher.PushFrameImpl(System.Windows.Threading.DispatcherFrame frame) Unknown
PresentationFramework.dll!System.Windows.Application.RunDispatcher(object ignore) Unknown
PresentationFramework.dll!System.Windows.Application.RunInternal(System.Windows.Window window) Unknown
> ProInspectX14x64.exe!ProInspectX.App.Main() Line 48 C#
我怎么知道哪个FrameworkElement导致了异常？