do not enforce creation of child nodes, if node cannot be searched anyway

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

@@ -48,6 +48,10 @@ namespace ICSharpCode.SharpDevelop.Dom.ClassBrowser
 			return null;
 		}
 		
+		public override bool CanFindChildNodeRecursively {
+			get { return false; }
+		}
+		
 		public bool HasBaseTypes()
 		{
 			ITypeDefinition currentTypeDef = definition.Resolve();

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

@@ -50,6 +50,10 @@ namespace ICSharpCode.SharpDevelop.Dom.ClassBrowser
 			return null;
 		}
 		
+		public override bool CanFindChildNodeRecursively {
+			get { return false; }
+		}
+		
 		public bool HasDerivedTypes()
 		{
 			ITypeDefinition currentTypeDef = definition.Resolve();

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

@@ -119,9 +119,10 @@ namespace ICSharpCode.SharpDevelop.Dom
 				}
 				
 				// Search in all children of this node
-				child.EnsureLazyChildren();
-				if (child is ModelCollectionTreeNode) {
-					foundNode = ((ModelCollectionTreeNode) child).FindChildNodeRecursively(predicate);
+				var modelNode = child as ModelCollectionTreeNode;
+				if (modelNode != null && modelNode.CanFindChildNodeRecursively) {
+					child.EnsureLazyChildren();
+					foundNode = modelNode.FindChildNodeRecursively(predicate);
 					if (foundNode != null)
 						break;
 				}
@@ -129,6 +130,10 @@ namespace ICSharpCode.SharpDevelop.Dom
 			
 			return foundNode;
 		}
+		
+		public virtual bool CanFindChildNodeRecursively {
+			get { return true; }
+		}
 		#endregion
 	}