I have a tree structured diagram with a variety of nodes recursively emanating from a single root. Each node has a single link that connects it from its parent. When I have Ctrl-Click selected a number of nodes, then Ctrl-Click and drag the mouse to select more, I get an InvalidOperationException. Visual Studio does not indicate that any of my own code has been invoked in a nested way. I am not making any nodes or links in these selections.

Thanks for any tips.

Stack trace below:

+

$exception
{"Collection was modified; enumeration operation may not execute."}
System.Exception {System.InvalidOperationException}

>
mscorlib.dll!System.Collections.ArrayList.ArrayListEnumeratorSimple.MoveNext() + 0x119 bytes

MindFusion.Diagramming.dll!MindFusion.Diagramming.Selection.x6e950a5680221e52() + 0xb1 bytes

MindFusion.Diagramming.dll!MindFusion.Diagramming.Selection.CompleteCreate(Syste
m.Drawing.PointF end = {X = 102.54689 Y = 62.0782051}) + 0x6c bytes

MindFusion.Diagramming.dll!MindFusion.Diagramming.InteractionState.Complete(Syst
em.Drawing.PointF point = {X = 102.54689 Y = 62.0782051}, MindFusion.Diagramming.Diagram diagram = {MindFusion.Diagramming.Diagram}) + 0x4fe bytes

MindFusion.Diagramming.WinForms.dll!MindFusion.Diagramming.WinForms.Behaviors.Be
haviorBase.OnMouseUp(System.Drawing.Point mousePosition = {X = 995 Y = 691}, System.Windows.Forms.MouseButtons mouseButton = Left) + 0x6b3 bytes

MindFusion.Diagramming.WinForms.dll!MindFusion.Diagramming.WinForms.DiagramView.
OnMouseUp(System.Windows.Forms.MouseEventArgs e = {X = 995 Y = 691 Button = Left}) + 0x36e bytes

System.Windows.Forms.dll!System.Windows.Forms.Control.WmMouseUp(ref System.Windows.Forms.Message m, System.Windows.Forms.MouseButtons button, int clicks) + 0x28f bytes

System.Windows.Forms.dll!System.Windows.Forms.Control.WndProc(ref System.Windows.Forms.Message m) + 0x885 bytes

System.Windows.Forms.dll!System.Windows.Forms.Control.ControlNativeWindow.OnMess
age(ref System.Windows.Forms.Message m) + 0x10 bytes

System.Windows.Forms.dll!System.Windows.Forms.Control.ControlNativeWindow.WndPro
c(ref System.Windows.Forms.Message m) + 0x31 bytes

System.Windows.Forms.dll!System.Windows.Forms.NativeWindow.DebuggableCallback(Sy
stem.IntPtr hWnd, int msg = 514, System.IntPtr wparam, System.IntPtr lparam) + 0x57 bytes

[Native to Managed Transition]

[Managed to Native Transition]

System.Windows.Forms.dll!System.Windows.Forms.Application.ComponentManager.Syste
m.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(int dwComponentID, int reason = -1, int pvLoopData = 0) + 0x24e bytes

System.Windows.Forms.dll!System.Windows.Forms.Application.ThreadContext.RunMessa
geLoopInner(int reason = -1, System.Windows.Forms.ApplicationContext context = {Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.WinFormsA
ppContext}) + 0x177 bytes

System.Windows.Forms.dll!System.Windows.Forms.Application.ThreadContext.RunMessa
geLoop(int reason, System.Windows.Forms.ApplicationContext context) + 0x61 bytes

System.Windows.Forms.dll!System.Windows.Forms.Application.Run(System.Windows.For
ms.ApplicationContext context) + 0x18 bytes

Microsoft.VisualBasic.dll!Microsoft.VisualBasic.ApplicationServices.WindowsForms
ApplicationBase.OnRun() + 0x81 bytes

Microsoft.VisualBasic.dll!Microsoft.VisualBasic.ApplicationServices.WindowsForms
ApplicationBase.DoApplicationModel() + 0xef bytes

Microsoft.VisualBasic.dll!Microsoft.VisualBasic.ApplicationServices.WindowsForms
ApplicationBase.Run(string[] commandLine) + 0x68 bytes

[Native to Managed Transition]

[Managed to Native Transition]

mscorlib.dll!System.AppDomain.ExecuteAssembly(string assemblyFile, System.Security.Policy.Evidence assemblySecurity, string[] args) + 0x3a bytes

Microsoft.VisualStudio.HostingProcess.Utilities.dll!Microsoft.VisualStudio.Hosti
ngProcess.HostProc.RunUsersAssembly() + 0x2b bytes

mscorlib.dll!System.Threading.ThreadHelper.ThreadStart_Context(object state) + 0x66 bytes

mscorlib.dll!System.Threading.ExecutionContext.Run(System.Threading.ExecutionCon
text executionContext, System.Threading.ContextCallback callback, object state) + 0x6f bytes

mscorlib.dll!System.Threading.ThreadHelper.ThreadStart() + 0x44 bytes

In one case, yes. However, before I do my own code, I get a List copy of the Selection (rather than doing my code in an iterator of Selection). Also, I notice that when I get the exception, the stack trace does not show any of my own code executing -- if my code was causing the issue, I would have expected to see my code on the stack trace. But I will try to reproduce this with breakpoints on all my possible code, to confirm for sure that it isn't executing.

That worked, thanks!