Bug 80429 [Preferences] [Dialogs] FieldEditors should relax requirements to support DialogPages
bundles/org.eclipse.jface/src/org/eclipse/jface/preference/FieldEditorPreferencePage.java
*/
    protected abstract void createFieldEditors();
    /**	
     * The field editor preference page implementation of an <code>IDialogPage</code>
     * method disposes of this page's controls and images.
     * Subclasses may override to release their own allocated SWT
     * resources, but must call <code>super.dispose</code>.
     */
    public void dispose() {
        super.dispose();
        if (fields != null) {
            Iterator e = fields.iterator();
            while (e.hasNext()) {
                FieldEditor pe = (FieldEditor) e.next();
                pe.setPreferencePage(null);
                pe.setPropertyChangeListener(null);
                pe.setPreferenceStore(null);
            }
        }
    }
    /**
     * Returns a parent composite for a field editor.
     * <p>
     * This value must not be cached since a new parent
     * may be created each time this method called. Thus
     * this method must be called each time a field editor
     * is constructed.
     * </p>
     *
     * @return a parent