Index: Core/Gui/src/Core.Gui/Forms/MainWindow/MainWindow.xaml.cs
===================================================================
diff -u -ra5af013e2d8df86949c9a86b1bc8bbc7412d074f -ra7d5b3a8be1cd68328a4c336db1124641d50e1c1
--- Core/Gui/src/Core.Gui/Forms/MainWindow/MainWindow.xaml.cs	(.../MainWindow.xaml.cs)	(revision a5af013e2d8df86949c9a86b1bc8bbc7412d074f)
+++ Core/Gui/src/Core.Gui/Forms/MainWindow/MainWindow.xaml.cs	(.../MainWindow.xaml.cs)	(revision a7d5b3a8be1cd68328a4c336db1124641d50e1c1)
@@ -601,8 +601,6 @@
         private void MainWindow_OnLoaded(object sender, RoutedEventArgs e)
         {
             WindowState = WindowState.Maximized;
-
-            ValidateItems();
         }
 
         private void OnViewOpened(object sender, ViewChangeEventArgs e)
@@ -620,6 +618,8 @@
             {
                 UpdateComponentsForView(viewController.ViewHost.ActiveDocumentView);
             }
+
+            UpdateToolWindowButtonState();
         }
 
         private void OnViewBroughtToFront(object sender, ViewChangeEventArgs e)
Index: Core/Gui/src/Core.Gui/GuiCore.cs
===================================================================
diff -u -r8ad6b3365d2cd05d3753cf188c10e8e06c3dca18 -ra7d5b3a8be1cd68328a4c336db1124641d50e1c1
--- Core/Gui/src/Core.Gui/GuiCore.cs	(.../GuiCore.cs)	(revision 8ad6b3365d2cd05d3753cf188c10e8e06c3dca18)
+++ Core/Gui/src/Core.Gui/GuiCore.cs	(.../GuiCore.cs)	(revision a7d5b3a8be1cd68328a4c336db1124641d50e1c1)
@@ -394,8 +394,6 @@
 
         private void ApplicationProjectOpened(IProject newProject)
         {
-            mainWindow.ValidateItems();
-
             projectObserver.Observable = newProject;
             UpdateProjectData();
             mainWindow.UpdateProjectExplorer();
@@ -460,8 +458,6 @@
                 {
                     ViewHost.BringToFront(mainWindow.ProjectExplorer);
                 }
-
-                mainWindow.ValidateItems();
             };
 
             mainWindow.Closing += delegate(object sender, CancelEventArgs e)