Bug 134266 [Wizard] Page description not set if page message already set
Since page messages such as errors and warnings used to be displayed in the same widget as the page description, code was put in place in WizardDialog#updateDescriptionMessage() to avoid setting the page description if there was already a message. As of 3.2 M6 there is a separate widget for displaying error and warning messages and so the page description should always be set.
bundles/org.eclipse.jface/src/org/eclipse/jface/wizard/WizardDialog.java
* it has an area at the top containing both the
 * wizard's title, description, and image; the actual wizard page
 * appears in the middle; below that is a progress indicator
 * (which is made visible if needed); and at the bottom
 * of the page is message line and a button bar containing 
 * Help, Next, Back, Finish, and Cancel buttons (or some subset).
 * </p>
 * <p>
 * Clients may subclass <code>WizardDialog</code>, although this
 * is rarely required.
 * </p>
 */
public class WizardDialog extends TitleAreaDialog implements IWizardContainer2, IPageChangeProvider {
    /**
     * Image registry key for error message image (value <code>"dialog_title_error_image"</code>).
     */
    public static final String WIZ_IMG_ERROR = "dialog_title_error_image"; 
    
    private IWizard wizard;
    
    private ArrayList createdWizards = new ArrayList();
    
    private ArrayList nestedWizards = new ArrayList();
    
    private IWizardPage currentPage = null;
    	
    private long activeRunningOperations = 0;
    
    private String pageMessage;
    private int pageMessageType = IMessageProvider.NONE;