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
}
			}
			
			/*
			 * @see IJavaAnnotation#getOverlaidIterator()
			 */
			public Iterator getOverlaidIterator() {
				if (fOverlaids != null)
					return fOverlaids.iterator();
				return null;
			}
			
			public String getAnnotationType() {
				return fType;
			}
			/* (non-Javadoc)
			 * @see org.eclipse.jdt.internal.ui.javaeditor.IJavaAnnotation#getCompilationUnit()
			 */
			public ICompilationUnit getCompilationUnit() {
				return fCompilationUnit;
			}
		}
		
		/**
		 * Internal structure for mapping positions to some value. 
		 * The reason for this specific structure is that positions can
		 * change over time. Thus a lookup is based on value and not
		 * on hash value.
		 */
		protected static class ReverseMap {