Index: /stable/HeuristicLab.Optimizer/3.3/OptimizerDockingMainForm.cs
===================================================================
--- /stable/HeuristicLab.Optimizer/3.3/OptimizerDockingMainForm.cs	(revision 10892)
+++ /stable/HeuristicLab.Optimizer/3.3/OptimizerDockingMainForm.cs	(revision 10893)
@@ -86,5 +86,5 @@
     protected override void OnClosing(CancelEventArgs e) {
       base.OnClosing(e);
-      if (MainFormManager.MainForm.Views.OfType<IContentView>().FirstOrDefault() != null) {
+      if (MainFormManager.MainForm.Views.OfType<IContentView>().Any(v=>v.Content is IStorableContent)) {
         if (MessageBox.Show(this, "Some views are still opened. If their content has not been saved, it will be lost after closing. Do you really want to close HeuristicLab Optimizer?", "Close Optimizer", MessageBoxButtons.YesNo, MessageBoxIcon.Question, MessageBoxDefaultButton.Button1) == DialogResult.No)
           e.Cancel = true;
@@ -110,5 +110,5 @@
       else {
         IContentView activeView = ActiveView as IContentView;
-        if ((activeView != null) && (activeView.Content != null) && (activeView.Content is IStorableContent)) {
+        if ((activeView != null) && (activeView.Content is IStorableContent)) {
           IStorableContent content = (IStorableContent)activeView.Content;
           Title = title + " [" + (string.IsNullOrEmpty(content.Filename) ? "Unsaved" : content.Filename) + "]";
Index: /stable/HeuristicLab.Optimizer/3.3/OptimizerMultipleDocumentMainForm.cs
===================================================================
--- /stable/HeuristicLab.Optimizer/3.3/OptimizerMultipleDocumentMainForm.cs	(revision 10892)
+++ /stable/HeuristicLab.Optimizer/3.3/OptimizerMultipleDocumentMainForm.cs	(revision 10893)
@@ -86,5 +86,5 @@
     protected override void OnClosing(CancelEventArgs e) {
       base.OnClosing(e);
-      if (MainFormManager.MainForm.Views.OfType<IContentView>().FirstOrDefault() != null) {
+      if (MainFormManager.MainForm.Views.OfType<IContentView>().Any(v => v.Content is IStorableContent)) {
         if (MessageBox.Show(this, "Some views are still opened. If their content has not been saved, it will be lost after closing. Do you really want to close HeuristicLab Optimizer?", "Close Optimizer", MessageBoxButtons.YesNo, MessageBoxIcon.Question, MessageBoxDefaultButton.Button1) == DialogResult.No)
           e.Cancel = true;
@@ -110,5 +110,5 @@
       else {
         IContentView activeView = ActiveView as IContentView;
-        if ((activeView != null) && (activeView.Content != null) && (activeView.Content is IStorableContent)) {
+        if ((activeView != null) && (activeView.Content is IStorableContent)) {
           IStorableContent content = (IStorableContent)activeView.Content;
           Title = title + " [" + (string.IsNullOrEmpty(content.Filename) ? "Unsaved" : content.Filename) + "]";
Index: /stable/HeuristicLab.Optimizer/3.3/OptimizerSingleDocumentMainForm.cs
===================================================================
--- /stable/HeuristicLab.Optimizer/3.3/OptimizerSingleDocumentMainForm.cs	(revision 10892)
+++ /stable/HeuristicLab.Optimizer/3.3/OptimizerSingleDocumentMainForm.cs	(revision 10893)
@@ -86,5 +86,5 @@
     protected override void OnClosing(CancelEventArgs e) {
       base.OnClosing(e);
-      if (MainFormManager.MainForm.Views.OfType<IContentView>().FirstOrDefault() != null) {
+      if (MainFormManager.MainForm.Views.OfType<IContentView>().Any(v => v.Content is IStorableContent)) {
         if (MessageBox.Show(this, "Some views are still opened. If their content has not been saved, it will be lost after closing. Do you really want to close HeuristicLab Optimizer?", "Close Optimizer", MessageBoxButtons.YesNo, MessageBoxIcon.Question, MessageBoxDefaultButton.Button1) == DialogResult.No)
           e.Cancel = true;
@@ -110,5 +110,5 @@
       else {
         IContentView activeView = ActiveView as IContentView;
-        if ((activeView != null) && (activeView.Content != null) && (activeView.Content is IStorableContent)) {
+        if ((activeView != null) && (activeView.Content is IStorableContent)) {
           IStorableContent content = (IStorableContent)activeView.Content;
           Title = title + " [" + (string.IsNullOrEmpty(content.Filename) ? "Unsaved" : content.Filename) + "]";
