Index: Core/Common/test/Core.Common.Gui.Test/Forms/MainWindow/MainWindowTest.cs
===================================================================
diff -u -r00f45b1bba92f5171087885039c8b8261860a1ba -re59a206ea06e40bbc9959cd98fc1a10ae7cdcf8c
--- Core/Common/test/Core.Common.Gui.Test/Forms/MainWindow/MainWindowTest.cs	(.../MainWindowTest.cs)	(revision 00f45b1bba92f5171087885039c8b8261860a1ba)
+++ Core/Common/test/Core.Common.Gui.Test/Forms/MainWindow/MainWindowTest.cs	(.../MainWindowTest.cs)	(revision e59a206ea06e40bbc9959cd98fc1a10ae7cdcf8c)
@@ -23,6 +23,8 @@
 using System.ComponentModel;
 using System.Linq;
 using System.Windows;
+using Core.Common.Base.Data;
+using Core.Common.Base.Storage;
 using Core.Common.Controls.Views;
 using Core.Common.Gui.Forms.MainWindow;
 using Core.Common.Gui.Forms.MessageWindow;
@@ -411,5 +413,65 @@
             }
             mocks.VerifyAll();
         }
+
+        [Test]
+        [STAThread]
+        public void GivenGuiWithPropertyGrid_ClosingPropertyGrid_PropertyGridPropertySetToNull()
+        {
+            // Setup
+            var mocks = new MockRepository();
+            var projectStore = mocks.Stub<IStoreProject>();
+            var projectFactory = mocks.Stub<IProjectFactory>();
+            mocks.ReplayAll();
+
+            using (var mainWindow = new Gui.Forms.MainWindow.MainWindow())
+            using (var gui = new GuiCore(mainWindow, projectStore, projectFactory, new GuiCoreSettings()))
+            {
+                gui.Run();
+
+                mainWindow.SetGui(gui);
+                mainWindow.InitializeToolWindows();
+
+                // Precondition
+                Assert.IsNotNull(mainWindow.PropertyGrid);
+
+                // Call
+                mainWindow.ViewHost.Remove(mainWindow.PropertyGrid);
+
+                // Assert
+                Assert.IsNull(mainWindow.PropertyGrid);
+            }
+            mocks.VerifyAll();
+        }
+
+        [Test]
+        [STAThread]
+        public void GivenGuiWithMessageWindow_ClosingMessageWindow_MessageWindowPropertySetToNull()
+        {
+            // Setup
+            var mocks = new MockRepository();
+            var projectStore = mocks.Stub<IStoreProject>();
+            var projectFactory = mocks.Stub<IProjectFactory>();
+            mocks.ReplayAll();
+
+            using (var mainWindow = new Gui.Forms.MainWindow.MainWindow())
+            using (var gui = new GuiCore(mainWindow, projectStore, projectFactory, new GuiCoreSettings()))
+            {
+                gui.Run();
+
+                mainWindow.SetGui(gui);
+                mainWindow.InitializeToolWindows();
+
+                // Precondition
+                Assert.IsNotNull(mainWindow.MessageWindow);
+
+                // Call
+                mainWindow.ViewHost.Remove(mainWindow.MessageWindow);
+
+                // Assert
+                Assert.IsNull(mainWindow.MessageWindow);
+            }
+            mocks.VerifyAll();
+        }
     }
 }
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