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/CompilationUnitDocumentProvider.java
Position position= createPositionFromProblem(problem);
							if (position != null) {
								try {
									ProblemAnnotation annotation= new ProblemAnnotation(problem, cu);
									addAnnotation(annotation, position, false);
									overlayMarkers(position, annotation);								
									fGeneratedAnnotations.add(annotation);
									
									temporaryProblemsChanged= true;
								} catch (BadLocationException x) {
									
								}
							}
						}
						
						fCollectedProblems.clear();
					}
					
					removeMarkerOverlays(isCanceled);
					fPreviouslyOverlaid.clear();
					fPreviouslyOverlaid= null;
				}
					
				if (temporaryProblemsChanged)
					fireModelChanged();
			}
			
			private void removeMarkerOverlays(boolean isCanceled) {
				if (isCanceled) {
					fCurrentlyOverlaid.addAll(fPreviouslyOverlaid);