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
IVerticalRuler v= getVerticalRuler();
		if (fLineNumberRulerColumn != null && v instanceof CompositeRuler) {
			CompositeRuler c= (CompositeRuler) v;
			c.removeDecorator(fLineNumberRulerColumn);
			fLineNumberRulerColumn= null;
		}
		if (fIsChangeInformationShown)
			showChangeRuler(true);
	}
	
	/**
	 * Return whether the line number ruler column should be 
	 * visible according to the preference store settings.
	 * 
	 * @return <code>true</code> if the line numbers should be visible
	 */
	private boolean isLineNumberRulerVisible() {
		IPreferenceStore store= getPreferenceStore();
		return store.getBoolean(LINE_NUMBER_RULER);
	}
	
	/**
	 * Returns whether quick diff info should be visible upon opening an editor 
	 * according to the preference store settings.
	 * 
	 * @return <code>true</code> if the line numbers should be visible
	 * @since R3.0
	 */
	private boolean isQuickDiffAlwaysOn() {
		IPreferenceStore store= getPreferenceStore();