Index: trunk/sources/HeuristicLab.Core.Views/3.3/ItemArrayView.cs
===================================================================
--- trunk/sources/HeuristicLab.Core.Views/3.3/ItemArrayView.cs	(revision 3455)
+++ trunk/sources/HeuristicLab.Core.Views/3.3/ItemArrayView.cs	(revision 3456)
@@ -196,12 +196,12 @@
     #region ListView Events
     protected virtual void itemsListView_SelectedIndexChanged(object sender, EventArgs e) {
-      addButton.Enabled = itemsListView.SelectedItems.Count > 0 && !Content.IsReadOnly && !ReadOnly;
+      addButton.Enabled = itemsListView.SelectedItems.Count > 0 && (Content != null) && !Content.IsReadOnly && !ReadOnly;
       moveUpButton.Enabled = itemsListView.SelectedItems.Count == 1 &&
                              itemsListView.SelectedIndices[0] != 0 &&
-                             !Content.IsReadOnly && !ReadOnly;
+                             (Content != null) && !Content.IsReadOnly && !ReadOnly;
       moveDownButton.Enabled = itemsListView.SelectedItems.Count == 1 &&
                                itemsListView.SelectedIndices[0] != itemsListView.Items.Count - 1 &&
-                               !Content.IsReadOnly && !ReadOnly;
-      removeButton.Enabled = itemsListView.SelectedItems.Count > 0 && !Content.IsReadOnly && !ReadOnly;
+                               (Content != null) && !Content.IsReadOnly && !ReadOnly;
+      removeButton.Enabled = itemsListView.SelectedItems.Count > 0 && (Content != null) && !Content.IsReadOnly && !ReadOnly;
 
       if (itemsListView.SelectedItems.Count == 1) {
Index: trunk/sources/HeuristicLab.Core.Views/3.3/ItemCollectionView.cs
===================================================================
--- trunk/sources/HeuristicLab.Core.Views/3.3/ItemCollectionView.cs	(revision 3455)
+++ trunk/sources/HeuristicLab.Core.Views/3.3/ItemCollectionView.cs	(revision 3456)
@@ -167,5 +167,5 @@
     #region ListView Events
     protected virtual void itemsListView_SelectedIndexChanged(object sender, EventArgs e) {
-      removeButton.Enabled = !Content.IsReadOnly && !ReadOnly && itemsListView.SelectedItems.Count > 0;
+      removeButton.Enabled = (Content != null) && !Content.IsReadOnly && !ReadOnly && itemsListView.SelectedItems.Count > 0;
       if (itemsListView.SelectedItems.Count == 1) {
         T item = (T)itemsListView.SelectedItems[0].Tag;
Index: trunk/sources/HeuristicLab.Core.Views/3.3/ItemListView.cs
===================================================================
--- trunk/sources/HeuristicLab.Core.Views/3.3/ItemListView.cs	(revision 3455)
+++ trunk/sources/HeuristicLab.Core.Views/3.3/ItemListView.cs	(revision 3456)
@@ -193,10 +193,10 @@
       moveUpButton.Enabled = itemsListView.SelectedItems.Count == 1 &&
                              itemsListView.SelectedIndices[0] != 0 &&
-                             !Content.IsReadOnly && !ReadOnly;
+                             (Content != null) && !Content.IsReadOnly && !ReadOnly;
       moveDownButton.Enabled = itemsListView.SelectedItems.Count == 1 &&
                                itemsListView.SelectedIndices[0] != itemsListView.Items.Count - 1 &&
-                               !Content.IsReadOnly && !ReadOnly;
+                               (Content != null) && !Content.IsReadOnly && !ReadOnly;
       removeButton.Enabled = itemsListView.SelectedItems.Count > 0 &&
-                             !Content.IsReadOnly && !ReadOnly;
+                             (Content != null) && !Content.IsReadOnly && !ReadOnly;
 
       if (itemsListView.SelectedItems.Count == 1) {
Index: trunk/sources/HeuristicLab.Optimization.Views/3.3/RunCollectionView.cs
===================================================================
--- trunk/sources/HeuristicLab.Optimization.Views/3.3/RunCollectionView.cs	(revision 3455)
+++ trunk/sources/HeuristicLab.Optimization.Views/3.3/RunCollectionView.cs	(revision 3456)
@@ -163,5 +163,5 @@
     #region ListView Events
     protected virtual void itemsListView_SelectedIndexChanged(object sender, EventArgs e) {
-      removeButton.Enabled = itemsListView.SelectedItems.Count > 0 && !Content.IsReadOnly && !ReadOnly;
+      removeButton.Enabled = itemsListView.SelectedItems.Count > 0 && (Content != null) && !Content.IsReadOnly && !ReadOnly;
       if (itemsListView.SelectedItems.Count == 1) {
         IRun item = (IRun)itemsListView.SelectedItems[0].Tag;
