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
fCurrentEvent= new CompilationUnitAnnotationModelEvent(this, getResource());
			}
			
			/*
			 * @see IProblemRequestor#isActive()
			 */
			public boolean isActive() {
				return fIsActive && (fCollectedProblems != null);
			}
			
			/*
			 * @see IProblemRequestorExtension#setProgressMonitor(IProgressMonitor)
			 */
			public void setProgressMonitor(IProgressMonitor monitor) {
				fProgressMonitor= monitor;
			}
			
			/*
			 * @see IProblemRequestorExtension#setIsActive(boolean)
			 */
			public void setIsActive(boolean isActive) {
				if (fIsActive != isActive) {
					fIsActive= isActive;
					if (fIsActive)
						startCollectingProblems();
					else
						stopCollectingProblems();
				}
			}