diff --git a/src/Main/Base/Project/Src/Gui/Dialogs/OptionPanels/ProjectOptions/ApplicationSettings.cs b/src/Main/Base/Project/Src/Gui/Dialogs/OptionPanels/ProjectOptions/ApplicationSettings.cs
index 2b342ab7db..5e0ae6a7cf 100644
--- a/src/Main/Base/Project/Src/Gui/Dialogs/OptionPanels/ProjectOptions/ApplicationSettings.cs
+++ b/src/Main/Base/Project/Src/Gui/Dialogs/OptionPanels/ProjectOptions/ApplicationSettings.cs
@@ -81,7 +81,7 @@ namespace ICSharpCode.SharpDevelop.Gui.OptionPanels
 			// re-evaluate if the project has the minimum version whenever this options page gets visible
 			// because the "convert project" button on the compiling tab page might have updated the MSBuild version.
 			applicationManifestComboBox.VisibleChanged += delegate {
-				applicationManifestComboBox.Enabled = project.MinimumSolutionVersion >= 10;
+				applicationManifestComboBox.Enabled = project.MinimumSolutionVersion >= Solution.SolutionVersionVS2008;
 			};
 			
 			Get<TextBox>("projectFolder").Text = project.Directory;
diff --git a/src/Main/Base/Project/Src/Gui/Dialogs/ProjectOptionsView.cs b/src/Main/Base/Project/Src/Gui/Dialogs/ProjectOptionsView.cs
index 11fd84d7ab..a82774ba2f 100644
--- a/src/Main/Base/Project/Src/Gui/Dialogs/ProjectOptionsView.cs
+++ b/src/Main/Base/Project/Src/Gui/Dialogs/ProjectOptionsView.cs
@@ -7,6 +7,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using System.IO;
 
 using ICSharpCode.Core;
@@ -67,5 +68,13 @@ namespace ICSharpCode.SharpDevelop.Project.Dialogs
 			}
 			project.Save();
 		}
+		
+		public override void Dispose()
+		{
+			foreach (IDisposable op in tabControl.OptionPanels.OfType<IDisposable>()) {
+				op.Dispose();
+			}
+			base.Dispose();
+		}
 	}
 }
diff --git a/src/Main/Base/Project/Src/Gui/Dialogs/TabbedOptionsDialog.xaml.cs b/src/Main/Base/Project/Src/Gui/Dialogs/TabbedOptionsDialog.xaml.cs
index 91b7eac47f..c16eaedae8 100644
--- a/src/Main/Base/Project/Src/Gui/Dialogs/TabbedOptionsDialog.xaml.cs
+++ b/src/Main/Base/Project/Src/Gui/Dialogs/TabbedOptionsDialog.xaml.cs
@@ -2,6 +2,7 @@
 using System;
 using System.Collections.Generic;
 using System.Text;
+using System.Linq;
 using System.Windows;
 using System.Windows.Controls;
 using System.Windows.Data;
@@ -42,5 +43,13 @@ namespace ICSharpCode.SharpDevelop.Gui
 			this.DialogResult = false;
 			Close();
 		}
+		
+		protected override void OnClosed(EventArgs e)
+		{
+			base.OnClosed(e);
+			foreach (IDisposable op in tabbedOptions.OptionPanels.OfType<IDisposable>()) {
+				op.Dispose();
+			}
+		}
 	}
 }
\ No newline at end of file
diff --git a/src/Main/Base/Project/Src/Gui/Dialogs/TreeViewOptionsDialog.xaml.cs b/src/Main/Base/Project/Src/Gui/Dialogs/TreeViewOptionsDialog.xaml.cs
index 5076feee6e..031e6636b3 100644
--- a/src/Main/Base/Project/Src/Gui/Dialogs/TreeViewOptionsDialog.xaml.cs
+++ b/src/Main/Base/Project/Src/Gui/Dialogs/TreeViewOptionsDialog.xaml.cs
@@ -50,6 +50,14 @@ namespace ICSharpCode.SharpDevelop.Gui
 			Close();
 		}
 		
+		protected override void OnClosed(EventArgs e)
+		{
+			base.OnClosed(e);
+			foreach (IDisposable op in optionPanels.OfType<IDisposable>()) {
+				op.Dispose();
+			}
+		}
+		
 		List<IOptionPanel> optionPanels = new List<IOptionPanel>();
 		OptionPanelNode activeNode;