title: WPF extended toolkit PropertyGrid DateTime property updating issue
body: <p>There is a property of type DateTime in a propertygrid. Here is a code:</p>
  
  <h2>XAML</h2>
  
  <pre><code>&lt;xctk:PropertyGrid x:Name="_propertyGrid" Margin="10" AutoGenerateProperties="True" SelectedObject="{Binding}"&gt;
  
  &lt;/xctk:PropertyGrid&gt;
  </code></pre>
  
  <h2>C#</h2>
  
  <pre><code>public class DateEditor : Xceed.Wpf.Toolkit.PropertyGrid.Editors.ITypeEditor
      {
          public FrameworkElement ResolveEditor(Xceed.Wpf.Toolkit.PropertyGrid.PropertyItem propertyItem)
          {
  
              DateTimeUpDown temp1 = new DateTimeUpDown();
              temp1.Format = DateTimeFormat.Custom;
              temp1.FormatString = "dd.MM.yyyy hh:m:ss";
  
              //create the binding from the bound property item to the editor
              var _binding = new Binding("Value"); //bind to the Value property of the PropertyItem
              _binding.Source = propertyItem;
              _binding.ValidatesOnExceptions = true;
              _binding.ValidatesOnDataErrors = true;
              _binding.Mode = BindingMode.TwoWay;
  
              BindingOperations.SetBinding(temp1, DateTimeUpDown.TextProperty, _binding);
  
              return temp1;
          }
      }
  
  public class CustomAttributEditorPerson : INotifyPropertyChanged
      {
          private DateTime FDate;
  
          [Category("Information")]
          [DisplayName("Date")]
          //This custom editor is a Class that implements the ITypeEditor interface
          [RefreshProperties(RefreshProperties.All)]
          [Editor(typeof(FirstNameEditor), typeof(FirstNameEditor))]
          public DateTime Date
          {
              get
              {
                  return this.FDate;
              }
              set
              {
                  this.FDate = value;
                  NotifyPropertyChanged("Date");
              }
          }
  
          public event PropertyChangedEventHandler PropertyChanged;
  
          private void NotifyPropertyChanged(String info)
          {
              if (PropertyChanged != null)
              {
                  PropertyChanged(this, new PropertyChangedEventArgs(info));
              }
          }
      }
  
  public partial class MainWindow : Window
      {
          CustomAttributEditorPerson temp = new CustomAttributEditorPerson();
  
          public MainWindow()
          {
              InitializeComponent();
  
              temp.Date = new DateTime(2020, 7, 7, 0, 1, 2);
  
              _propertyGrid.SelectedObject = temp;
          }
  </code></pre>
  
  <p>When app is started I see current date instead of required 7.7.2020. Changing of the property temp.Date doesn't reflected in propertygrid. The following code doesn't lead to the result:</p>
  
  <h2>C#</h2>
  
  <pre><code>private void Button_Click_1(object sender, RoutedEventArgs e)
          {
                temp.Date = new DateTime(2030, 8, 7, 0, 1, 2);   
                _propertyGrid.Update();        
          }
  </code></pre>
  
  <p>What should be done to reflect the changes of tempDate in propertygrid?
  Thanks for assistance.</p>