Nullreference exception on Treelistbox

Grids for WPF Forum

Posted 4 years ago by Miguel A.
Version: 18.1.0672
Platform: .NET 4.7
Environment: Windows 10 (64-bit)


randomly I'm getting a nullreference exception when trying to click on treeitems. It happens after time so I don't know exactly how to reproduce it


at ActiproSoftware.Windows.Controls.Grids.TreeListBoxItem.OnPointerPressed(Object sender, InputPointerButtonEventArgs e)
at ActiproSoftware.Windows.Input.InputAdapter.#doi(Object #xhb, InputEventArgs #yhb, InputPointerButtonKind #zYi)
at System.Windows.RoutedEventArgs.InvokeHandler(Delegate handler, Object target)
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.RaiseTrustedEvent(RoutedEventArgs args)
at System.Windows.Input.InputManager.ProcessStagingArea()
at System.Windows.Input.InputManager.ProcessInput(InputEventArgs input)
at System.Windows.Input.InputProviderSite.ReportInput(InputReport inputReport)
at System.Windows.Interop.HwndMouseInputProvider.ReportInput(IntPtr hwnd, InputMode mode, Int32 timestamp, RawMouseActions actions, Int32 x, Int32 y, Int32 wheel)
at System.Windows.Interop.HwndMouseInputProvider.FilterMessage(IntPtr hwnd, WindowMessage msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
at System.Windows.Interop.HwndSource.InputFilterMessage(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
at MS.Win32.HwndWrapper.WndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
at MS.Win32.HwndSubclass.DispatcherCallbackOperation(Object o)
at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs)
at System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Int32 numArgs, Delegate catchHandler)

When debugging at runtime with an external debugging software which disassembles the code (I hope this is oky for you) I found the line which seems to have a null references:

private void OnPointerPressed(object sender, InputPointerButtonEventArgs e)
if (e == null || e.Handled || !base.IsEnabled)
TreeListBox owner = this.treeNode.Owner; <----- At this line an exception is thrown



[Modified 4 years ago]

Comments (1)

Answer - Posted 4 years ago by Actipro Software Support - Cleveland, OH, USA

Hi Miguel,

Yes there should have been a null check on that.  It's the only spot in that method where there wasn't one.  We've fixed it for the next maintenance release.  If you need a preview build in the meantime to work around this, please write our support address.

Actipro Software Support

The latest build of this product (v22.1.3) was released 29 days ago, which was after the last post in this thread.

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