Hello Huanhe,

I have been trying to reproduce this exception on my side, but to no avail .Would you attach a small project replicating this so I can investigate it further.

Thanks in advance.

Regards Petar.

Hello Patar,

Thanks for your reply. I still got a window designer problem as I said in my previous post . Please see the details below:

'GridInfragistics is a user control
Private Sub GridInfragistics_Loaded(ByVal sender As Object, ByVal e As System.Windows.RoutedEventArgs) Handles Me.Loaded
        If CellHeight > 0 Then
            grdTable.FieldSettings.CellHeight = CellHeight 'CellHeight is a dependency property
        End If  
End Sub

Here are the errors I got in a desinger window when I when I tried to load the user control in a window:

System.NullReferenceException
Object reference not set to an instance of an object.
   at UserControlsSpecific.GridInfragistics.GridInfragistics_Loaded(Object sender, RoutedEventArgs e) in C:\UserControlsSpecific\GridInfragistics.xaml.vb:line 35
   at System.Windows.RoutedEventHandlerInfo.InvokeHandler(Object target, RoutedEventArgs routedEventArgs)
   at System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised)
   at System.Windows.UIElement.RaiseEventImpl(DependencyObject sender, RoutedEventArgs args)
   at System.Windows.UIElement.RaiseEvent(RoutedEventArgs e)
   at System.Windows.BroadcastEventHelper.BroadcastEvent(DependencyObject root, RoutedEvent routedEvent)
   at System.Windows.BroadcastEventHelper.BroadcastLoadedEvent(Object root)
   at MS.Internal.LoadedOrUnloadedOperation.DoWork()
   at System.Windows.Media.MediaContext.FireLoadedPendingCallbacks()
   at System.Windows.Media.MediaContext.FireInvokeOnRenderCallbacks()
   at System.Windows.Media.MediaContext.RenderMessageHandlerCore(Object resizedCompositionTarget)
   at System.Windows.Media.MediaContext.RenderMessageHandler(Object resizedCompositionTarget)
   at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs)
   at MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen(Object source, Delegate method, Object args, Int32 numArgs, Delegate catchHandler)

This error didn't affect the runtime performance. It maybe some thing wrong with my other parts of code. But if you could provide a working example by wrapping an xamDataGrid in a user control
with a dependency property and load that user control in another window, it will be great.