[Sorry if this is a duplicate.  I hit post but after refreshing the screen several times I did not see my previous post]

We are getting a Null Reference exception when a use Shift+Clicks an Item in the Timetable grid.  We have a custom item class that derives from appointment.  We did not however override the LoadFrom or SaveTo serialization methods, nor are we registering this new Item class with the Schedule.  We don't intend on using this functionality as we are SOA and persist everything server side.  From the call stack it looks like it might be a problem that we are not providing clone and/or serialization codes?  How should we get past this error?  Any way to turn off this feature?

Call stack:
Message:    "Object reference not set to an instance of an object."

Source:     "Calendar"
Stack:

   at MindFusion.Scheduling.Appointment.Clone()

   at MindFusion.Scheduling.WinForms.Calendar.OnMouseDown(MouseEventArgs e)

   at System.Windows.Forms.Control.WmMouseDown(Message& m, MouseButtons button, Int32 clicks)

   at System.Windows.Forms.Control.WndProc(Message& m)

   at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)

   at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)

   at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)


Thanks again

Ok, I changed ItemCloneKey to None (and for good measure ItemChangeRefKey to None also - it turns out Alt+Click would also cause a runtime error).

Unfortunately this also generates a Null Ref. runtime error, although the stack is different, whenever I click an Item in the timetable:

   at MindFusion.Scheduling.WinForms.ItemTool..ctor(Calendar calendar, Item active, Item[] items, ItemToolAction action, Point initialMouse, TimeSpan minLength, Boolean canChangeReference)
   at MindFusion.Scheduling.WinForms.Calendar.OnMouseDown(MouseEventArgs e)
   at System.Windows.Forms.Control.WmMouseDown(Message& m, MouseButtons button, Int32 clicks)
   at System.Windows.Forms.Control.WndProc(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
   at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)

I will send you some code separately so you can take a look at the custom item class and maybe figure out what is going on.
In the meantime I will set the clone key back to shift, because at least then I don't get an unhandled thread exception when I click without having a modifier key pressed. (Note that ctl+click never seems to cause an error).

Thank you.  This solved our issue with modifier key + click events.  We decided not to override the property as setting it to null caused this problem.