void VTChanged(object sender, VisualTreeChangeEventArgs e) { var parentSourInfo = e.Parent == null ? null : VisualDiagnostics.GetXamlSourceInfo(e.Parent); var childSourInfo = VisualDiagnostics.GetXamlSourceInfo(e.Child); if (childSourInfo == null) { failures++; } if (e.Parent != null && parentSourInfo == null) { failures++; } }