Incorporate some feedback.

src/AddIns/Debugger/Debugger.AddIn/Visualizers/PresentationBindings/GridViewColumnHider.cs

@@ -29,9 +29,8 @@ namespace Debugger.AddIn.Visualizers
 				if (isVisible == value) return;
 				isVisible = value;
 				OnPropertyChanged();
-				var isVisibleChanged = this.IsVisibleChanged;
-				if (isVisibleChanged != null) {
-					isVisibleChanged(this, EventArgs.Empty);
+				if (IsVisibleChanged != null) {
+					IsVisibleChanged(this, EventArgs.Empty);
 				}
 			}
 		}

src/AddIns/Debugger/Debugger.AddIn/Visualizers/Utils/DebuggerHelpers.cs

@@ -65,24 +65,16 @@ namespace Debugger.AddIn.Visualizers.Utils
 			return refVal.GetValue();
 		}
 		
-		/// <summary>
-		/// Returns true if this type is enum.
-		/// </summary>
-		public static bool IsEnum(this IType type)
-		{
-			return type.DirectBaseTypes.Select(t => t.FullName).Contains("System.Enum");
-		}
-		
 		/// <summary>
 		/// Returns true is this type is System.Object.
 		/// </summary>
 		public static bool IsSystemDotObject(this IType type)
 		{
-			return type.FullName == "System.Object";
+			return type.IsKnownType(KnownTypeCode.Object);
 		}
 		
 		/// <summary>
-		/// Checks whether given type is a primitive type, String, or enum.
+		/// Returns true if given type is a primitive type, String, or enum.
 		/// </summary>
 		public static bool IsAtomic(this IType type)
 		{