Use NullSafeSimpleModelCollection where possible

src/AddIns/Debugger/Debugger.AddIn/Pads/ClassBrowserSupport.cs

@@ -67,7 +67,8 @@ namespace ICSharpCode.SharpDevelop.Gui.Pads
 			if (process == null)
 				throw new ArgumentNullException("process");
 			this.process = process;
-			this.modules = new SimpleModelCollection<Debugger.Module>(this.process.Modules);
+			this.modules = new NullSafeSimpleModelCollection<Debugger.Module>();
+			this.modules.AddRange(this.process.Modules);
 			this.process.ModuleLoaded += ModuleLoaded;
 			this.process.ModuleUnloaded += ModuleUnloaded;
 		}

src/AddIns/Misc/PackageManagement/Project/Src/Design/FakePackageManagementProjectService.cs

@@ -40,7 +40,7 @@ namespace ICSharpCode.PackageManagement.Design
 			}
 		}
 		
-		public readonly SimpleModelCollection<IModelCollection<IProject>> ProjectCollections = new SimpleModelCollection<IModelCollection<IProject>>();
+		public readonly IMutableModelCollection<IModelCollection<IProject>> ProjectCollections = new NullSafeSimpleModelCollection<IModelCollection<IProject>>();
 		IModelCollection<IProject> allProjects;
 		
 		public IModelCollection<IProject> AllProjects {

src/AddIns/Misc/PackageManagement/Test/Src/Helpers/ProjectHelper.cs

@@ -18,7 +18,7 @@ namespace PackageManagement.Tests.Helpers
 			SD.InitializeForUnitTests();
 			ISolution solution = MockRepository.GenerateStrictMock<ISolution>();
 			solution.Stub(s => s.MSBuildProjectCollection).Return(new Microsoft.Build.Evaluation.ProjectCollection());
-			solution.Stub(s => s.Projects).Return(new SimpleModelCollection<IProject>());
+			solution.Stub(s => s.Projects).Return(new NullSafeSimpleModelCollection<IProject>());
 			solution.Stub(s => s.ActiveConfiguration).Return(new ConfigurationAndPlatform("Debug", "Any CPU"));
 			//solution.Stub(s => s.FileName).Return(FileName.Create(@"d:\projects\Test\TestSolution.sln"));
 			return solution;

src/Main/Base/Project/Dom/ClassBrowser/IClassBrowser.cs

@@ -21,7 +21,7 @@ namespace ICSharpCode.SharpDevelop.Dom.ClassBrowser
 		public AssemblyList()
 		{
 			Name = "<default>";
-			Assemblies = new SimpleModelCollection<IAssemblyModel>();
+			Assemblies = new NullSafeSimpleModelCollection<IAssemblyModel>();
 		}
 	}
 }

src/Main/Base/Project/Dom/SimpleModelCollection.cs

@@ -16,7 +16,7 @@ namespace ICSharpCode.SharpDevelop.Dom
 	/// </summary>
 	public class SimpleModelCollection<T> : IMutableModelCollection<T>
 	{
-		readonly ModelCollectionChangedEvent<T> collectionChangedEvent;
+		readonly ModelCollectionChangedEvent<T> collectionChangedEvent = new ModelCollectionChangedEvent<T>();
 		readonly List<T> list;
 		List<T> addedItems;
 		List<T> removedItems;
@@ -24,13 +24,13 @@ namespace ICSharpCode.SharpDevelop.Dom
 		public SimpleModelCollection()
 		{
 			this.list = new List<T>();
-			collectionChangedEvent = new ModelCollectionChangedEvent<T>();
 		}
 		
 		public SimpleModelCollection(IEnumerable<T> items)
 		{
 			this.list = new List<T>(items);
-			collectionChangedEvent = new ModelCollectionChangedEvent<T>();
+			// Note: intentionally not using ValidateItem(), as calling a virtual method
+			// from a constructor is problematic
 		}
 		
 		protected void CheckReentrancy()
@@ -39,6 +39,9 @@ namespace ICSharpCode.SharpDevelop.Dom
 				throw new InvalidOperationException("Cannot modify the collection from within the CollectionChanged event.");
 		}
 		
+		/// <summary>
+		/// Called before an item
+		/// </summary>
 		protected virtual void ValidateItem(T item)
 		{
 		}
@@ -182,16 +185,21 @@ namespace ICSharpCode.SharpDevelop.Dom
 			if (items == null)
 				throw new ArgumentNullException("items");
 			CheckReentrancy();
-			List<T> itemsList = items.ToList();
-			for (int i = 0; i < itemsList.Count; i++) {
-				ValidateItem(itemsList[i]);
-			}
-			for (int i = 0; i < itemsList.Count; i++) {
-				OnAdd(itemsList[i]);
+			try {
+				foreach (T item in items) {
+					// Add each item before validating the next,
+					// this is necessary because ValidateItem() might be checking
+					// for duplicates (e.g. KeyedModelCollection<,>)
+					ValidateItem(item);
+					OnAdd(item);
+					list.Add(item);
 				}
-			list.AddRange(itemsList);
+			} finally {
+				// In case validation fails, we still need to raise the event
+				// for the items that were added successfully.
 				RaiseEventIfNotInBatch();
 			}
+		}
 		
 		public bool Remove(T item)
 		{

src/Main/Base/Project/Dom/SynchronizedModelCollection.cs

@@ -31,10 +31,17 @@ namespace ICSharpCode.SharpDevelop.Dom
 			this.syncRoot = syncRoot;
 		}
 		
-		// Event registration is thread-safe on the underlying collection
 		public event ModelCollectionChangedEventHandler<T> CollectionChanged {
-			add { underlyingCollection.CollectionChanged += value; }
-			remove { underlyingCollection.CollectionChanged -= value; }
+			add {
+				lock (syncRoot) {
+					underlyingCollection.CollectionChanged += value;
+				}
+			}
+			remove {
+				lock (syncRoot) {
+					underlyingCollection.CollectionChanged -= value;
+				}
+			}
 		}
 
 		#region IMutableModelCollection implementation

src/Main/Base/Project/Src/Project/AbstractProject.cs

@@ -196,7 +196,7 @@ namespace ICSharpCode.SharpDevelop.Project
 		#endregion
 		
 		#region ProjectSections
-		SimpleModelCollection<SolutionSection> projectSections = new SimpleModelCollection<SolutionSection>();
+		SimpleModelCollection<SolutionSection> projectSections = new NullSafeSimpleModelCollection<SolutionSection>();
 		
 		[Browsable(false)]
 		public IMutableModelCollection<SolutionSection> ProjectSections {

src/Main/SharpDevelop/Dom/ClassBrowser/OpenFromGacDialog.xaml

@@ -1,5 +1,6 @@
 <Window
 	x:Class="ICSharpCode.SharpDevelop.Dom.ClassBrowser.OpenFromGacDialog"
+	x:ClassModifier="internal"
 	xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
 	xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
 	xmlns:core="http://icsharpcode.net/sharpdevelop/core"

src/Main/SharpDevelop/Dom/ClassBrowser/OpenFromGacDialog.xaml.cs

@@ -35,7 +35,7 @@ namespace ICSharpCode.SharpDevelop.Dom.ClassBrowser
 	/// <summary>
 	/// Interaction logic for OpenFromGacDialog.xaml
 	/// </summary>
-	public partial class OpenFromGacDialog : Window
+	internal partial class OpenFromGacDialog : Window
 	{
 		ObservableCollection<GacEntry> gacEntries = new ObservableCollection<GacEntry>();
 		ObservableCollection<GacEntry> filteredEntries = new ObservableCollection<GacEntry>();

src/Main/SharpDevelop/Project/ProjectService.cs

@@ -17,7 +17,7 @@ namespace ICSharpCode.SharpDevelop.Project
 	{
 		public SDProjectService()
 		{
-			allSolutions = new SimpleModelCollection<ISolution>();
+			allSolutions = new NullSafeSimpleModelCollection<ISolution>();
 			allProjects = allSolutions.SelectMany(s => s.Projects);
 			
 			SD.GetFutureService<IWorkbench>().ContinueWith(t => t.Result.ActiveViewContentChanged += ActiveViewContentChanged);