Bug 40785 [plan item] Overview ruler improvements
- navigation from ruler to editor - hovering over header area shows number of errors/warning (header annotations in general)
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/javaeditor/filebuffers/CompilationUnitDocumentProvider2.java
private ICompilationUnit fCompilationUnit;
			private List fCollectedProblems;
			private List fGeneratedAnnotations;
			private IProgressMonitor fProgressMonitor;
			private boolean fIsActive= false;
			
			private ReverseMap fReverseMap= new ReverseMap();
			private List fPreviouslyOverlaid= null; 
			private List fCurrentlyOverlaid= new ArrayList();
			private CompilationUnitAnnotationModelEvent fCurrentEvent;
			public CompilationUnitAnnotationModel(IResource resource) {
				super(resource);
				fCurrentEvent= new CompilationUnitAnnotationModelEvent(this, getResource());
			}
			
			public void setCompilationUnit(ICompilationUnit unit)  {