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
/* (non-Javadoc)
     * @see org.eclipse.jface.wizard.IWizardContainer2#updateSize()
     */
    public void updateSize() {
        updateSize(currentPage);
    }
    /**
     * Computes the correct dialog size for the given page and resizes 
     * its shell if nessessary.
     *
     * @param page the wizard page
     */
    private void updateSizeForPage(IWizardPage page) {
        
        Point delta = calculatePageSizeDelta(page);
        if (delta.x > 0 || delta.y > 0) {
             
            Shell shell = getShell();
            Point shellSize = shell.getSize();
            setShellSize(shellSize.x + delta.x, shellSize.y + delta.y);
            constrainShellSize();
        }
    }
    /**
     * Computes the correct dialog size for the given wizard and resizes 
     * its shell if nessessary.
     *
     * @param sizingWizard the wizard
     */
    private void updateSizeForWizard(IWizard sizingWizard) {