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
* @param mw the margin width
         * @param mh the margin height
         * @param minW the minimum width
         * @param minH the minimum height
         */
        public PageContainerFillLayout(int mw, int mh, int minW, int minH) {
            marginWidth = mw;
            marginHeight = mh;
            minimumWidth = minW;
            minimumHeight = minH;
        }
        /* (non-Javadoc)
         * Method declared on Layout.
         */
        public Point computeSize(Composite composite, int wHint, int hHint,
                boolean force) {
            if (wHint != SWT.DEFAULT && hHint != SWT.DEFAULT) {
				return new Point(wHint, hHint);
			}
            Point result = null;
            Control[] children = composite.getChildren();
            if (children.length > 0) {
                result = new Point(0, 0);
                for (int i = 0; i < children.length; i++) {
                    Point cp = children[i].computeSize(wHint, hHint, force);
                    result.x = Math.max(result.x, cp.x);
                    result.y = Math.max(result.y, cp.y);
                }
                result.x = result.x + 2 * marginWidth;
                result.y = result.y + 2 * marginHeight;