Bug 96917 [implementation] If two editors use the 2.x-compatible API, one or both doesn't work
At least one problem is that 3.0 installs partitioners for every editor that might possibly edit a file, but each editor expects its own partitioner to be installed. Leading to the famous white screen with blue line.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/javaeditor/CompilationUnitDocumentProvider.java
*/
			protected AnnotationModelEvent createAnnotationModelEvent() {
				return new CompilationUnitAnnotationModelEvent(this, getResource());
			}
			protected Position createPositionFromProblem(IProblem problem) {
				int start= problem.getSourceStart();
				if (start < 0)
					return null;
				int length= problem.getSourceEnd() - problem.getSourceStart() + 1;
				if (length < 0)
					return null;
				return new Position(start, length);
			}
			/*
			 * @see IProblemRequestor#beginReporting()
			 */
			public void beginReporting() {
				ProblemRequestorState state= (ProblemRequestorState) fProblemRequestorState.get();
				if (state == null)
					internalBeginReporting(false);
			}
			/*
			 * @see org.eclipse.jdt.internal.ui.text.java.IProblemRequestorExtension#beginReportingSequence()
			 */
			public void beginReportingSequence() {
				ProblemRequestorState state= (ProblemRequestorState) fProblemRequestorState.get();
				if (state == null)
					internalBeginReporting(true);
			}
			/**