Show a Rectangle when a Property is set!

(like in the VS2012 Property Grid)

src/AddIns/DisplayBindings/WpfDesign/WpfDesign.Designer/Project/Converters.cs

@@ -9,6 +9,7 @@ using System.Windows.Data;
 using System.Globalization;
 using System.Windows;
 using System.Collections;
+using System.Windows.Media;
 
 namespace ICSharpCode.WpfDesign.Designer.Converters
 {
@@ -85,7 +86,7 @@ namespace ICSharpCode.WpfDesign.Designer.Converters
 		{
 			if (value == null || (int)value == 0) {
 				return Visibility.Collapsed;
-			}			
+			}
 			return Visibility.Visible;
 		}
 
@@ -145,17 +146,35 @@ namespace ICSharpCode.WpfDesign.Designer.Converters
 	}
 	
 	public class FormatDoubleConverter : IValueConverter
-    {
-        [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Security", "CA2104:DoNotDeclareReadOnlyMutableReferenceTypes", Justification = "converter is immutable")]
-        public static readonly FormatDoubleConverter Instance=new FormatDoubleConverter();
+	{
+		[System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Security", "CA2104:DoNotDeclareReadOnlyMutableReferenceTypes", Justification = "converter is immutable")]
+		public static readonly FormatDoubleConverter Instance=new FormatDoubleConverter();
 
-        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
-        {
-            return Math.Round((double)value);
-        }
-        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
+		public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
+		{
+			return Math.Round((double)value);
+		}
+		public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
 		{
 			throw new NotImplementedException();
 		}
-    }
+	}
+	
+	public class BlackWhenTrue : IValueConverter
+	{
+		[System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Security", "CA2104:DoNotDeclareReadOnlyMutableReferenceTypes", Justification = "converter is immutable")]
+		public static readonly BlackWhenTrue Instance = new BlackWhenTrue();
+
+		private Brush black = new SolidColorBrush(Colors.Black);
+
+		public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
+		{
+			return (bool)value ? black : null;
+		}
+
+		public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
+		{
+			throw new NotImplementedException();
+		}
+	}
 }

src/AddIns/DisplayBindings/WpfDesign/WpfDesign.Designer/Project/PropertyGrid/PropertyGridView.xaml

@@ -199,6 +199,7 @@
 							              Style="{StaticResource ExpandButtonStyle}"
 							              IsChecked="{Binding IsExpanded}"
 							              Visibility="{Binding HasChildren, Converter={x:Static Converters:HiddenWhenFalse.Instance}}" />
+							<Rectangle Width="8" Height="8" Stroke="Black" Fill="{Binding IsSet, Converter={x:Static Converters:BlackWhenTrue.Instance}}" StrokeThickness="1" DockPanel.Dock="Right" Margin="4,0,4,0" VerticalAlignment="Center"/>							
 							<TextBlock Text="{Binding Name}"
 							           TextTrimming="CharacterEllipsis"
 							           VerticalAlignment="Center"