Bug 41443 overview ruler not working
smoke test for 20030812 The overview ruler in the Java editor does not work when starting with a fresh workspace as described in the smoke test scenario.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/javaeditor/JavaEditor.java
* @since R3.0
	 */
	private void showChangeRuler(boolean show) {
		IVerticalRuler v= getVerticalRuler();
		if (v instanceof CompositeRuler) {
			CompositeRuler c= (CompositeRuler) v;
			if (show && fChangeRulerColumn == null)
				c.addDecorator(1, createChangeRulerColumn());
			else if (!show && fChangeRulerColumn != null) {
				c.removeDecorator(fChangeRulerColumn);
				fChangeRulerColumn= null;
			}
		}
	}
	/**
	 * Shows the line number ruler column.
	 */
	private void showLineNumberRuler() {
		showChangeRuler(false);
		IVerticalRuler v= getVerticalRuler();
		if (v instanceof CompositeRuler) {
			CompositeRuler c= (CompositeRuler) v;
			c.addDecorator(1, createLineNumberRulerColumn());
		}
	}
	
	/**
	 * Hides the line number ruler column.
	 */
	private void hideLineNumberRuler() {