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
private String pageDescription;
    
    private ProgressMonitorPart progressMonitorPart;
    private Cursor waitCursor;
    private Cursor arrowCursor;
    private MessageDialog windowClosingDialog;
    
    private Button backButton;
    private Button nextButton;
    private Button finishButton;
    private Button cancelButton;
    private Button helpButton;
    private SelectionAdapter cancelListener;
    private boolean isMovingToPreviousPage = false;
    private Composite pageContainer;
    private PageContainerFillLayout pageContainerLayout = new PageContainerFillLayout(
            5, 5, 300, 225);
    private int pageWidth = SWT.DEFAULT;
    private int pageHeight = SWT.DEFAULT;
    private static final String FOCUS_CONTROL = "focusControl"; 
    private boolean lockedUI = false;
	
    private ListenerList pageChangedListeners = new ListenerList();
    /**
     * A layout for a container which includes several pages, like
     * a notebook, wizard, or preference dialog. The size computed by
     * this layout is the maximum width and height of all pages currently
     * inserted into the container.
     */
    protected class PageContainerFillLayout extends Layout {