Bug 54900 [rulers] Java Editor does not show ruler on external Java files
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/javaeditor/CompilationUnitDocumentProvider.java
* @param monitor the parent progress monitor
	 * @param ticks the number of work ticks allocated from the parent monitor
	 * @return the new sub-progress monitor
	 */
	private IProgressMonitor getSubProgressMonitor(IProgressMonitor monitor, int ticks) {
		if (monitor != null)
			return new SubProgressMonitor(monitor, ticks, SubProgressMonitor.PREPEND_MAIN_LABEL_TO_SUBTASK);
		return new NullProgressMonitor();
	}
	protected void commitWorkingCopy(IProgressMonitor monitor, Object element, final CompilationUnitInfo info, boolean overwrite) throws CoreException {
		if (monitor == null)
			monitor= new NullProgressMonitor();
		monitor.beginTask("", 100); 
		try {
			final IProgressMonitor subMonitor1= getSubProgressMonitor(monitor, 50);
			try {
				Platform.run(new ISafeRunnable() {
					public void run() {
						try {
							info.fCopy.reconcile(ICompilationUnit.NO_AST, false, null, subMonitor1);
						} catch (JavaModelException ex) {
							handleException(ex);
						} catch (OperationCanceledException ex) {
							
						}
					}
					public void handleException(Throwable ex) {
						IStatus status= new Status(IStatus.ERROR, JavaUI.ID_PLUGIN, IStatus.OK, "Error in JDT Core during reconcile while saving", ex);  
						JavaPlugin.getDefault().getLog().log(status);
					}