Bug 168888 [Wizards] PageTransition classes may need rename/reorg
bundles/org.eclipse.jface/src/org/eclipse/jface/wizard/WizardDialog.java
*/
    protected void buttonPressed(int buttonId) {
        switch (buttonId) {
        case IDialogConstants.HELP_ID: {
            helpPressed();
            break;
        }
        case IDialogConstants.BACK_ID: {
            backPressed();
            break;
        }
        case IDialogConstants.NEXT_ID: {
            nextPressed();
            break;
        }
        case IDialogConstants.FINISH_ID: {
            finishPressed();
            break;
        }
        
        }
    }
    /**
     * Calculates the difference in size between the given
     * page and the page container. A larger page results 
     * in a positive delta.
     *
     * @param page the page
     * @return the size difference encoded
     *   as a <code>new Point(deltaWidth,deltaHeight)</code>