title: Trace.Assert not breaking, neither showing the message box
body: <p>I have a WPF application in which I'm moving data around on a Canvas.
  The problem started when I tried moving the data with the mouse like a freak.</p>
  
  <p>Here's the sequence of the actions:</p>
  
  <ul>
  <li>The MouseMove on the Canvas is triggered</li>
  <li>In the MouseMove, I change some data</li>
  <li>A Trace.Assert FAILS.  The debugger does not break, neither is the message box</li>
  <li>Another MouseMove is triggered</li>
  <li>The data is changed again</li>
  <li>An exception is thrown because of a reentrancy check in a collection. The debugger breaks there.  The Assert message box was never shown.</li>
  </ul>
  
  <p>The big problem here is that I can go back to the assert, but it's not the data at the time the assert failed, but the modified data at the end... so basically I can't debug that correctly.</p>
  
  <p>Here's the stack trace, starting from the first MouseMove (Notice the ShowMessageBoxAssert and the fact that it still goes on...):</p>
  
  <pre>
    .Models.FCurve.MoveKey(int keyIndex = 3, double keyTime = 1182.0) Line 199 C#
    .Models.FCurve.KeyTimeChanged(Models.FCurveKey timeChangeKey = {Models.FCurveKey}) Line 186 + 0x2d bytes C#
    .Models.FCurve.AddKeyToArray.AnonymousMethod(object sender = {Models.FCurveKey}, System.EventArgs args = {System.EventArgs}) Line 163 + 0x11 bytes C#
    [Native to Managed Transition] 
    [Managed to Native Transition] 
    .Models.FCurveKey.OnTimeChanged() Line 45 + 0x14 bytes C#
    .Models.FCurveKey..ctor.AnonymousMethod(object sender = {FCurveEditorTestApp.Impl.FCurveKeyImpl}, System.EventArgs args = {System.EventArgs}) Line 18 + 0x8 bytes C#
    [Native to Managed Transition] 
    [Managed to Native Transition] 
    FCurveEditorTestApp.exe!FCurveEditorTestApp.Impl.FCurveKeyImpl.OnTimeChanged() Line 43 + 0x14 bytes C#
    FCurveEditorTestApp.exe!FCurveEditorTestApp.Impl.FCurveKeyImpl.Time.set(double value = 1182.0) Line 34 + 0x8 bytes C#
    .Models.FCurveKey.Time.set(double value = 1182.0) Line 36 + 0x1b bytes C#
    .ViewModels.CurveKeyViewModel.X.set(double value = 1182.0) Line 32 + 0x2b bytes C#
    .ViewModels.CurveAreaViewModel.MoveSelectedItem.AnonymousMethod(ViewModels.CurveKeyViewModel key = {ViewModels.CurveKeyViewModel}) Line 127 + 0x2d bytes C#
    Collections.CollectionHelper.ForEach(System.Collections.Generic.IEnumerable source = {System.Linq.Enumerable.OfTypeIterator}, System.Action action = {Method = {Void b__8(ViewModels.CurveKeyViewModel)}}) Line 31 + 0xe bytes C#
    .ViewModels.CurveAreaViewModel.MoveSelectedItem(double deltaX = 693.0, double deltaY = 35.0) Line 126 + 0x63 bytes C#
    .Views.CurveAreaView._AreaCanvas_MouseMove(object sender = {System.Windows.Controls.Canvas}, System.Windows.Input.MouseEventArgs e = {System.Windows.Input.MouseEventArgs}) Line 195 + 0x2d bytes C#
    PresentationCore.dll!System.Windows.Input.MouseEventArgs.InvokeEventHandler(System.Delegate genericHandler, object genericTarget) + 0x34 bytes 
    PresentationCore.dll!System.Windows.RoutedEventArgs.InvokeHandler(System.Delegate handler, object target) + 0x27 bytes 
    PresentationCore.dll!System.Windows.RoutedEventHandlerInfo.InvokeHandler(object target, System.Windows.RoutedEventArgs routedEventArgs) + 0x3e bytes 
    PresentationCore.dll!System.Windows.EventRoute.InvokeHandlersImpl(object source = {System.Windows.Controls.Canvas}, System.Windows.RoutedEventArgs args = {System.Windows.Input.MouseEventArgs}, bool reRaised = false) + 0x1bf bytes 
    PresentationCore.dll!System.Windows.UIElement.RaiseEventImpl(System.Windows.DependencyObject sender = {System.Windows.Controls.Canvas}, System.Windows.RoutedEventArgs args = {System.Windows.Input.MouseEventArgs}) + 0x79 bytes 
    PresentationCore.dll!System.Windows.UIElement.RaiseEvent(System.Windows.RoutedEventArgs args = {System.Windows.Input.MouseEventArgs}, bool trusted) + 0x35 bytes 
    PresentationCore.dll!System.Windows.Input.InputManager.ProcessStagingArea() + 0x311 bytes 
    PresentationCore.dll!System.Windows.Input.InputManager.ProcessInput(System.Windows.Input.InputEventArgs input) + 0x42 bytes 
    PresentationCore.dll!System.Windows.Input.InputProviderSite.ReportInput(System.Windows.Input.InputReport inputReport) + 0x62 bytes 
    PresentationCore.dll!System.Windows.Interop.HwndMouseInputProvider.ReportInput(System.IntPtr hwnd, System.Windows.Input.InputMode mode, int timestamp, System.Windows.Input.RawMouseActions actions, int x, int y, int wheel) + 0x2e2 bytes 
    PresentationCore.dll!System.Windows.Interop.HwndMouseInputProvider.FilterMessage(System.IntPtr hwnd = 2628604, int msg = 512, System.IntPtr wParam = 1, System.IntPtr lParam = 30409804, ref bool handled = false) + 0x22b bytes 
    PresentationCore.dll!System.Windows.Interop.HwndSource.InputFilterMessage(System.IntPtr hwnd = 2628604, int msg = 512, System.IntPtr wParam = 1, System.IntPtr lParam = 30409804, ref bool handled = false) + 0x75 bytes 
    WindowsBase.dll!MS.Win32.HwndWrapper.WndProc(System.IntPtr hwnd = 2628604, int msg = 512, System.IntPtr wParam = 1, System.IntPtr lParam = 30409804, ref bool handled = false) + 0xbe bytes 
    WindowsBase.dll!MS.Win32.HwndSubclass.DispatcherCallbackOperation(object o) + 0x7a bytes 
    WindowsBase.dll!System.Windows.Threading.ExceptionWrapper.InternalRealCall(System.Delegate callback = {Method = {System.Object DispatcherCallbackOperation(System.Object)}}, object args = {MS.Win32.HwndSubclass.DispatcherOperationCallbackParameter}, bool isSingleParameter = true) + 0x8a bytes 
    WindowsBase.dll!System.Windows.Threading.ExceptionWrapper.TryCatchWhen(object source = {System.Windows.Threading.Dispatcher}, System.Delegate callback, object args, bool isSingleParameter, System.Delegate catchHandler = null) + 0x4a bytes 
    WindowsBase.dll!System.Windows.Threading.Dispatcher.WrappedInvoke(System.Delegate callback, object args, bool isSingleParameter, System.Delegate catchHandler) + 0x44 bytes 
    WindowsBase.dll!System.Windows.Threading.Dispatcher.InvokeImpl(System.Windows.Threading.DispatcherPriority priority, System.TimeSpan timeout, System.Delegate method, object args, bool isSingleParameter) + 0x91 bytes 
    WindowsBase.dll!System.Windows.Threading.Dispatcher.Invoke(System.Windows.Threading.DispatcherPriority priority, System.Delegate method, object arg) + 0x40 bytes 
    WindowsBase.dll!MS.Win32.HwndSubclass.SubclassWndProc(System.IntPtr hwnd = 2628604, int msg = 512, System.IntPtr wParam = 1, System.IntPtr lParam = 30409804) + 0xdc bytes 
    [Native to Managed Transition] 
    [Managed to Native Transition] 
    System.dll!System.Diagnostics.AssertWrapper.ShowMessageBoxAssert(string stackTrace, string message, string detailMessage) + 0x103 bytes 
    System.dll!System.Diagnostics.DefaultTraceListener.Fail(string message, string detailMessage) + 0xb2 bytes 
    System.dll!System.Diagnostics.DefaultTraceListener.Fail(string message) + 0xa bytes 
    System.dll!System.Diagnostics.TraceInternal.Fail(string message = "") + 0xb6 bytes 
    System.dll!System.Diagnostics.Trace.Assert(bool condition) + 0x1c bytes 
    .ViewModels.CurvePathViewModel.CurvePathViewModel(Models.FCurveKey startKey = {Models.FCurveKey}, Models.FCurveKey endKey = {Models.FCurveKey}, ViewModels.IInterpolationProvider interpolatorProvider = {ViewModels.InterpolationInfoProvider}) Line 29 + 0x4e bytes C#
    .ViewModels.CurvePathViewModel.CurvePathViewModel(ViewModels.CurveKeyViewModel startKey = {ViewModels.CurveKeyViewModel}, ViewModels.CurveKeyViewModel endKey = {ViewModels.CurveKeyViewModel}, ViewModels.IInterpolationProvider interpolatorProvider = {ViewModels.InterpolationInfoProvider}) Line 20 + 0x81 bytes C#
    .ViewModels.CurveViewModel.UpdateSegmentForKey(ViewModels.CurveKeyViewModel key = {ViewModels.CurveKeyViewModel}) Line 215 + 0x41 bytes C#
    .ViewModels.CurveViewModel.KeyViewModelsChanged(object sender = Count = 13, System.Collections.Specialized.NotifyCollectionChangedEventArgs e = {System.Collections.Specialized.NotifyCollectionChangedEventArgs}) Line 187 + 0x30 bytes C#
    [Native to Managed Transition] 
    [Managed to Native Transition] 
    WindowsBase.dll!System.Collections.ObjectModel.ObservableCollection.OnCollectionChanged(System.Collections.Specialized.NotifyCollectionChangedEventArgs e) + 0x50 bytes 
    WindowsBase.dll!System.Collections.ObjectModel.ObservableCollection.OnCollectionChanged(System.Collections.Specialized.NotifyCollectionChangedAction action, object item, int index, int oldIndex) + 0x34 bytes 
    WindowsBase.dll!System.Collections.ObjectModel.ObservableCollection.MoveItem(int oldIndex, int newIndex) + 0x6f bytes 
    WindowsBase.dll!System.Collections.ObjectModel.ObservableCollection.Move(int oldIndex, int newIndex) + 0xe bytes 
    Collections.CollectionSynchronizer._SourceList_CollectionChanged(object sender = Count = 13, System.Collections.Specialized.NotifyCollectionChangedEventArgs e = {System.Collections.Specialized.NotifyCollectionChangedEventArgs}) Line 239 + 0x45 bytes C#
    [Native to Managed Transition] 
    [Managed to Native Transition] 
    WindowsBase.dll!System.Collections.ObjectModel.ReadOnlyObservableCollection.OnCollectionChanged(System.Collections.Specialized.NotifyCollectionChangedEventArgs args) + 0x1d bytes 
    WindowsBase.dll!System.Collections.ObjectModel.ReadOnlyObservableCollection.HandleCollectionChanged(object sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e) + 0xe bytes 
    [Native to Managed Transition] 
    [Managed to Native Transition] 
    WindowsBase.dll!System.Collections.ObjectModel.ObservableCollection.OnCollectionChanged(System.Collections.Specialized.NotifyCollectionChangedEventArgs e) + 0x50 bytes 
    WindowsBase.dll!System.Collections.ObjectModel.ObservableCollection.OnCollectionChanged(System.Collections.Specialized.NotifyCollectionChangedAction action, object item, int index, int oldIndex) + 0x34 bytes 
    WindowsBase.dll!System.Collections.ObjectModel.ObservableCollection.MoveItem(int oldIndex, int newIndex) + 0x6f bytes 
    WindowsBase.dll!System.Collections.ObjectModel.ObservableCollection.Move(int oldIndex, int newIndex) + 0xe bytes 
    .Models.FCurve.MoveKey(int keyIndex = 1, double keyTime = 489.0) Line 199 + 0x19 bytes C#
    .Models.FCurve.KeyTimeChanged(Models.FCurveKey timeChangeKey = {Models.FCurveKey}) Line 186 + 0x2d bytes C#
    .Models.FCurve.AddKeyToArray.AnonymousMethod(object sender = {Models.FCurveKey}, System.EventArgs args = {System.EventArgs}) Line 163 + 0x11 bytes C#
    [Native to Managed Transition] 
    [Managed to Native Transition] 
    .Models.FCurveKey.OnTimeChanged() Line 45 + 0x14 bytes C#
    .Models.FCurveKey..ctor.AnonymousMethod(object sender = {FCurveEditorTestApp.Impl.FCurveKeyImpl}, System.EventArgs args = {System.EventArgs}) Line 18 + 0x8 bytes C#
    [Native to Managed Transition] 
    [Managed to Native Transition] 
    FCurveEditorTestApp.exe!FCurveEditorTestApp.Impl.FCurveKeyImpl.OnTimeChanged() Line 43 + 0x14 bytes C#
    FCurveEditorTestApp.exe!FCurveEditorTestApp.Impl.FCurveKeyImpl.Time.set(double value = 489.0) Line 34 + 0x8 bytes C#
    .Models.FCurveKey.Time.set(double value = 489.0) Line 36 + 0x1b bytes C#
    .ViewModels.CurveKeyViewModel.X.set(double value = 489.0) Line 32 + 0x2b bytes C#
    .ViewModels.CurveAreaViewModel.MoveSelectedItem.AnonymousMethod(ViewModels.CurveKeyViewModel key = {ViewModels.CurveKeyViewModel}) Line 127 + 0x2d bytes C#
    Collections.CollectionHelper.ForEach(System.Collections.Generic.IEnumerable source = {System.Linq.Enumerable.OfTypeIterator}, System.Action action = {Method = {Void b__8(ViewModels.CurveKeyViewModel)}}) Line 31 + 0xe bytes C#
    .ViewModels.CurveAreaViewModel.MoveSelectedItem(double deltaX = 82.0, double deltaY = -9.0) Line 126 + 0x63 bytes C#
    Views.CurveAreaView._AreaCanvas_MouseMove(object sender = {System.Windows.Controls.Canvas}, System.Windows.Input.MouseEventArgs e = {System.Windows.Input.MouseEventArgs}) Line 195 + 0x2d bytes C#
  </pre>
  
  <p>The question would be: Why could this happen, and what should I do to make it break at the Assert time?</p>
  
  <p>I thought of using an exception, maybe for debugging, but it's really an assert that I need.  I'm thinking about all my others Asserts also, without needing to always convert them to exceptions for debugging...</p>