Bug 80473 [rulers][preferences] allow disabling of range indicator on left of java editor
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/javaeditor/JavaEditor.java
* @since 3.0
	 */
	private void installSemanticHighlighting() {
		if (fSemanticManager == null) {
			fSemanticManager= new SemanticHighlightingManager();
			fSemanticManager.install(this, (JavaSourceViewer) getSourceViewer(), JavaPlugin.getDefault().getJavaTextTools().getColorManager(), getPreferenceStore());
		}
	}
	/**
	 * Uninstall Semantic Highlighting.
	 *
	 * @since 3.0
	 */
	private void uninstallSemanticHighlighting() {
		if (fSemanticManager != null) {
			fSemanticManager.uninstall();
			fSemanticManager= null;
		}
	}
	/**
	 * Returns the Java element wrapped by this editors input.
	 *
	 * @return the Java element wrapped by this editors input.
	 * @since 3.0
	 */
	abstract protected IJavaElement getInputJavaElement();
	protected void updateStatusLine() {
		ITextSelection selection= (ITextSelection) getSelectionProvider().getSelection();
		Annotation annotation= getAnnotation(selection.getOffset(), selection.getLength());
		setStatusLineErrorMessage(null);