InvalidOperationException through ShowRulerThumbMarker

[Brian Sayatovic]

I didn't encounter this myself.  Instead, I saw it in our application logs.  We're using the Q1 2013 controls with the Windows 8 theme.

Any ideas?

System.InvalidOperationException: 4009 An error has occurred.
   at MS.Internal.XcpImports.CheckHResult(UInt32 hr)
   at MS.Internal.XcpImports.Collection_AddValue[T](PresentationFrameworkCollection`1 collection, CValue value)
   at MS.Internal.XcpImports.Collection_AddDependencyObject[T](PresentationFrameworkCollection`1 collection, DependencyObject value)
   at System.Windows.PresentationFrameworkCollection`1.AddDependencyObject(DependencyObject value)
   at System.Windows.Controls.UIElementCollection.AddInternal(UIElement value)
   at Telerik.Windows.Controls.RichTextBoxUI.DocumentRulerBase.ShowRulerThumbMarker(RulerThumb indent)
   at Telerik.Windows.Controls.RichTextBoxUI.DocumentRulerBase.TabStopThumb_DragStarted(Object sender, DragStartedEventArgs e)
   at Telerik.Windows.Controls.RichTextBoxUI.RulerThumb.StartDragging(Point origin)
   at Telerik.Windows.Controls.RichTextBoxUI.RulerThumb.OnMouseLeftButtonDown(MouseButtonEventArgs e)
   at System.Windows.Controls.Control.OnMouseLeftButtonDown(Control ctrl, EventArgs e)
   at MS.Internal.JoltHelper.FireEvent(IntPtr unmanagedObj, IntPtr unmanagedObjArgs, Int32 argsTypeIndex, Int32 actualArgsTypeIndex, String eventName, UInt32 flags) 0 Silverlight AppDomain

[Vasil]

Hello Brian,

Thank you for writing.

We have not observed this issue and have not received any similar reports. If you manage to reproduce the issue, please get back to us with further details, so that we could narrow down the cause of the problem and address it.

Regards,
Vasil
Telerik

[Brian Sayatovic]

I feel like I'm often in a game of chess and have reached a stalemate.  I can't consistently reproduce a problem, yet the problem is never resolved.

Does Telerik have any advice on how to narrow these sort of problems down?

If I had a convenient way to patch Teleriks' code, I would take every one of these issues and go and add diagnostic guards in the code.  Not to prevent the error (after all, we don't know what causes the error so we can't yet fix it), but to shed more light on it the next time it occurs.  This is what I do in my own code when there's a recurring problem I can't track down: I leave breadcrumbs.

But since I can't do that, what else can I do?  Is there a debug flag I can toggle to run Telerik (or Silverlight) with diagnostic debug output?

[Vasil]

Hi Brian,

Thank you for the feedback.

We do agree that such situations are not pleasant for either side and we do try to prevent not informative exceptions using different approaches. Most often the stack trace provides the hints as to where to look for the problem and how to reproduce it. This is also one of the reasons why the code is not obfuscated and we distribute pdb files along with the dlls.

In this particular case, it seems that the exception is thrown when a tab stop thumb and the accompanying line is added to the Panel that shows the tab stops and marker lines. There is no reason why we would suspect an exception would be thrown at that place, therefore the only information available is the stack trace of the exception. We will, however, consider some changes in the method so as to be able to track it down.

If you manage to find out relevant information on the cases when the problem can be observed, please share it with us, so that we can look into the problem sooner.


Regards,
Vasil
Telerik