diff --git a/src/Main/Base/Project/Src/Dom/IDecoration.cs b/src/Main/Base/Project/Src/Dom/IDecoration.cs
index 6b2a0cfccd..e23da782d5 100644
--- a/src/Main/Base/Project/Src/Dom/IDecoration.cs
+++ b/src/Main/Base/Project/Src/Dom/IDecoration.cs
@@ -46,6 +46,10 @@ namespace ICSharpCode.SharpDevelop.Dom
 			get;
 		}
 
+		/// <summary>
+		/// Gets if the member is virtual. Is true only if the "virtual" modifier was used, but non-virtual
+		/// members can be overridden, too; if they are already overriding a method.
+		/// </summary>
 		bool IsVirtual {
 			get;
 		}
@@ -86,6 +90,12 @@ namespace ICSharpCode.SharpDevelop.Dom
 		bool IsOverride {
 			get;
 		}
+		/// <summary>
+		/// Gets if the member can be overridden. Returns true when the member is "virtual" or "override" but not "sealed".
+		/// </summary>
+		bool IsOverridable {
+			get;
+		}
 		
 		bool IsNew {
 			get;
diff --git a/src/Main/Base/Project/Src/Dom/Implementations/AbstractDecoration.cs b/src/Main/Base/Project/Src/Dom/Implementations/AbstractDecoration.cs
index ff0dbc7b37..12afb67c04 100644
--- a/src/Main/Base/Project/Src/Dom/Implementations/AbstractDecoration.cs
+++ b/src/Main/Base/Project/Src/Dom/Implementations/AbstractDecoration.cs
@@ -164,6 +164,11 @@ namespace ICSharpCode.SharpDevelop.Dom
 				return (modifiers & ModifierEnum.Override) == ModifierEnum.Override;
 			}
 		}
+		public bool IsOverridable {
+			get {
+				return (IsOverride || IsVirtual) && !IsSealed;
+			}
+		}
 		public bool IsNew {
 			get {
 				return (modifiers & ModifierEnum.New) == ModifierEnum.New;
diff --git a/src/Main/Base/Project/Src/Dom/Implementations/DefaultReturnType.cs b/src/Main/Base/Project/Src/Dom/Implementations/DefaultReturnType.cs
index 606d0aff53..f78dfd5fd9 100644
--- a/src/Main/Base/Project/Src/Dom/Implementations/DefaultReturnType.cs
+++ b/src/Main/Base/Project/Src/Dom/Implementations/DefaultReturnType.cs
@@ -57,12 +57,15 @@ namespace ICSharpCode.SharpDevelop.Dom
 					
 					// do not add methods that were overridden
 					bool ok = true;
-					foreach (IMethod oldMethod in l) {
-						if (string.Equals(oldMethod.Name, m.Name, StringComparison.InvariantCultureIgnoreCase)) {
-							if (m.IsStatic == oldMethod.IsStatic) {
-								if (DiffUtility.Compare(oldMethod.Parameters, m.Parameters) == 0) {
-									ok = false;
-									break;
+					if (m.IsOverridable) {
+						StringComparer comparer = m.DeclaringType.ProjectContent.Language.NameComparer;
+						foreach (IMethod oldMethod in l) {
+							if (comparer.Equals(oldMethod.Name, m.Name)) {
+								if (m.IsStatic == oldMethod.IsStatic) {
+									if (DiffUtility.Compare(oldMethod.Parameters, m.Parameters) == 0) {
+										ok = false;
+										break;
+									}
 								}
 							}
 						}
@@ -84,12 +87,15 @@ namespace ICSharpCode.SharpDevelop.Dom
 				foreach (IProperty p in bc.Properties) {
 					// do not add methods that were overridden
 					bool ok = true;
-					foreach (IProperty oldProperty in l) {
-						if (string.Equals(oldProperty.Name, p.Name, StringComparison.InvariantCultureIgnoreCase)) {
-							if (p.IsStatic == oldProperty.IsStatic) {
-								if (DiffUtility.Compare(oldProperty.Parameters, p.Parameters) == 0) {
-									ok = false;
-									break;
+					if (p.IsOverridable) {
+						StringComparer comparer = p.DeclaringType.ProjectContent.Language.NameComparer;
+						foreach (IProperty oldProperty in l) {
+							if (comparer.Equals(oldProperty.Name, p.Name)) {
+								if (p.IsStatic == oldProperty.IsStatic) {
+									if (DiffUtility.Compare(oldProperty.Parameters, p.Parameters) == 0) {
+										ok = false;
+										break;
+									}
 								}
 							}
 						}
diff --git a/src/Main/StartUp/Project/Dialogs/ExceptionBox.cs b/src/Main/StartUp/Project/Dialogs/ExceptionBox.cs
index 833335208a..3a6afe41db 100644
--- a/src/Main/StartUp/Project/Dialogs/ExceptionBox.cs
+++ b/src/Main/StartUp/Project/Dialogs/ExceptionBox.cs
@@ -12,6 +12,7 @@ using System.Diagnostics;
 using System.Resources;
 using System.Reflection;
 using System.Drawing;
+using System.Threading;
 using System.Globalization;
 using ICSharpCode.Core;
 
@@ -93,7 +94,15 @@ namespace ICSharpCode.SharpDevelop
 		void CopyInfoToClipboard()
 		{
 			if (copyErrorCheckBox.Checked) {
-				ClipboardWrapper.SetText(getClipboardString());
+				if (Application.OleRequired() == ApartmentState.STA) {
+					ClipboardWrapper.SetText(getClipboardString());
+				} else {
+					Thread th = new Thread((ThreadStart)delegate {
+					                       	ClipboardWrapper.SetText(getClipboardString());
+					                       });
+					th.SetApartmentState(ApartmentState.STA);
+					th.Start();
+				}
 			}
 		}