Bug 74171 [preferences] Pref page; Restore defaults does not reset error status correctly
Version: 3.1.0 Build id: 200409140800 @@@@ Window/Preferences/Java/Editor/Hovers Select "Variable Values" Enter "Ctrl" as its hover. Delete "Ctrl" in text area so that it is empty. Click on "Restore Defaults". Observe the error will still be there.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/preferences/JavaEditorHoverConfigurationBlock.java
overlayKeys.add(new OverlayPreferenceStore.OverlayKey(OverlayPreferenceStore.BOOLEAN, PreferenceConstants.EDITOR_ANNOTATION_ROLL_OVER));
		overlayKeys.add(new OverlayPreferenceStore.OverlayKey(OverlayPreferenceStore.BOOLEAN, PreferenceConstants.EDITOR_SHOW_TEXT_HOVER_AFFORDANCE));
		overlayKeys.add(new OverlayPreferenceStore.OverlayKey(OverlayPreferenceStore.STRING, PreferenceConstants.EDITOR_TEXT_HOVER_MODIFIERS));
		overlayKeys.add(new OverlayPreferenceStore.OverlayKey(OverlayPreferenceStore.STRING, PreferenceConstants.EDITOR_TEXT_HOVER_MODIFIER_MASKS));
		
		OverlayPreferenceStore.OverlayKey[] keys= new OverlayPreferenceStore.OverlayKey[overlayKeys.size()];
		overlayKeys.toArray(keys);
		return keys;
	}
	/**
	 * Creates page for hover preferences.
	 * 
	 * @param parent the parent composite
	 * @return the control for the preference page
	 */
	public Control createControl(Composite parent) {
		Composite hoverComposite= new Composite(parent, SWT.NONE);
		GridLayout layout= new GridLayout();
		layout.numColumns= 2;
		hoverComposite.setLayout(layout);
		GridData gd= new GridData(GridData.FILL_BOTH);
		hoverComposite.setLayoutData(gd);
		String rollOverLabel= PreferencesMessages.getString("JavaEditorHoverConfigurationBlock.annotationRollover"); 
		addCheckBox(hoverComposite, rollOverLabel, PreferenceConstants.EDITOR_ANNOTATION_ROLL_OVER, 0); 
		
		fShowHoverAffordanceCheckbox= new Button(hoverComposite, SWT.CHECK);
		fShowHoverAffordanceCheckbox.setText(PreferencesMessages.getString("JavaEditorHoverConfigurationBlock.showAffordance")); 
		gd= new GridData(GridData.HORIZONTAL_ALIGN_BEGINNING);
		gd.horizontalIndent= 0;