Bug 17566 Browsing Java src not on class path
When browsing Java src which is not on the classpath it is annoying to have millions of Quickfix light bulbs and error indicators. I suggest to disable this feature and have a special icon in the editor tab to indicate that the source file is not on the classpath and therefore behaves differently in certain operations (search, quickfix, etc.)
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/javaeditor/CompilationUnitDocumentProvider.java
ICompilationUnit fCopy;
			
			CompilationUnitInfo(IDocument document, IAnnotationModel model, _FileSynchronizer fileSynchronizer, ICompilationUnit copy) {
				super(document, model, fileSynchronizer);
				fCopy= copy;
			}
			
			void setModificationStamp(long timeStamp) {
				fModificationStamp= timeStamp;
			}
		};
		
		/**
		 * Annotation representating an <code>IProblem</code>.
		 */
		static protected class ProblemAnnotation extends Annotation implements IProblemAnnotation {
			
			private List fOverlaids;
			private IProblem fProblem;
			private Image fImage;
			private static Image fgImage;