Infralution Support

[bhofmann]

Hello,

I'm joining the call stack of an exception that happened to a user of my application and that seem to be related to the virtual tree:

System.NullReferenceException: Der Objektverweis wurde nicht auf eine Objektinstanz festgelegt. ---> ApplicationThreadException: An unhandled exception occured
at Infralution.Controls.VirtualTree.Row.Reindex (System.Int32) in Row.cs:line 759
at Infralution.Controls.VirtualTree.Row.Reindex () in Row.cs:line 896
at Infralution.Controls.VirtualTree.Row.set_Expanded (System.Boolean) in Row.cs:line 205
at Infralution.Controls.VirtualTree.Row.Expand () in Row.cs:line 216
at Infralution.Controls.VirtualTree.RowWidget.ExpandRow () in RowWidget.cs:line 1471
at Infralution.Controls.VirtualTree.ExpansionWidget.OnMouseDown (System.Windows.Forms.MouseEventArgs) in ExpansionWidget.cs:line 148
at Infralution.Controls.WidgetControl.OnMouseDown (System.Windows.Forms.MouseEventArgs) in WidgetControl.cs:line 343
at Infralution.Controls.VirtualTree.VirtualTree.OnMouseDown (System.Windows.Forms.MouseEventArgs) in VirtualTree.cs:line 8508
at PHPEdit.Controls.VirtualTree.OnMouseDown (System.Windows.Forms.MouseEventArgs) in VirtualTree.cs:line 554
at System.Windows.Forms.Control.WmMouseDown (System.Windows.Forms.Message&, System.Windows.Forms.MouseButtons, System.Int32) in System.Windows.Forms:offset 142
at System.Windows.Forms.Control.WndProc (System.Windows.Forms.Message&) in System.Windows.Forms:offset 1181
at Infralution.Controls.BorderedControl.WndProc (System.Windows.Forms.Message&) in BorderedControl.cs:line 94
at Infralution.Controls.VirtualTree.VirtualTree.WndProc (System.Windows.Forms.Message&) in VirtualTree.cs:line 6879
at PHPEdit.Controls.VirtualTree.WndProc (System.Windows.Forms.Message&) in VirtualTree.cs:line 615
at System.Windows.Forms.Control+ControlNativeWindow.OnMessage (System.Windows.Forms.Message&) in System.Windows.Forms:offset 0
at System.Windows.Forms.Control+ControlNativeWindow.WndProc (System.Windows.Forms.Message&) in System.Windows.Forms:offset 142
at System.Windows.Forms.NativeWindow.Callback (System.IntPtr, System.Int32, System.IntPtr, System.IntPtr) in System.Windows.Forms:offset 37
--- End of inner exception stack trace ---
at PHPEdit.Exceptions.ExceptionHandler.Application_ThreadException (System.Object, System.Threading.ThreadExceptionEventArgs) in ExceptionHandler.cs:line 323
at System.Windows.Forms.Application+ThreadContext.OnThreadException (System.Exception) in System.Windows.Forms:offset 43
at System.Windows.Forms.Control.WndProcException (System.Exception) in System.Windows.Forms:offset 6
at System.Windows.Forms.Control+ControlNativeWindow.OnThreadException (System.Exception) in System.Windows.Forms:offset 12
at System.Windows.Forms.NativeWindow.Callback (System.IntPtr, System.Int32, System.IntPtr, System.IntPtr) in System.Windows.Forms:offset 65
at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW (System.Windows.Forms.NativeMethods+MSG&) in System.Windows.Forms:unknown location
at System.Windows.Forms.Application+ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop (System.Int32, System.Int32, System.Int32) in System.Windows.Forms:offset 380
at System.Windows.Forms.Application+ThreadContext.RunMessageLoopInner (System.Int32, System.Windows.Forms.ApplicationContext) in System.Windows.Forms:offset 478
at System.Windows.Forms.Application+ThreadContext.RunMessageLoop (System.Int32, System.Windows.Forms.ApplicationContext) in System.Windows.Forms:offset 19
at System.Windows.Forms.Application.Run (System.Windows.Forms.ApplicationContext) in System.Windows.Forms:offset 12
at PHPEdit.Program.Main (System.String[]) in Program.cs:line 52

Best regards,
Bastien Hofmann

[Infralution]

What version of Virtual Tree is the application using?

Is this exception happening repeatably?

Does your application use threads to update data in the tree?

Is your application handling GetChildren programmatically? Is so does the event handler potentially do something which may result in the tree being updated (either directly via UpdateRows or indirectly via a ListChanged notification from the data source)?
_________________
Infralution Support

[bhofmann]

Hello,

Thank you for your answer.

It was version 3.9.0.0 at the time of the crash, we have update to 3.10.0.0 since.
The exception has only be reported once by a user, so it's not repeatable easily.
I'm not accessing the tree by an other thread, at least not intentionnaly, the application contains many threads and I imagine it's possible that a tree gets updated by mistake as a side effect of another action, but I can't see what...
And we have overriden GetChildrenForRow, I'll have to check if we update the rows there, I'll let you know if I have more informations.

[Infralution]