Has that wrapper been implemented yet?
When it does, it will need to:
• be consistent for all overlay-style plugins (dialog, datepicker, etc)
• given a widget-specific class for non-theme targeting (though it will be statically positioned). Something like ui-widget-overlay-wrap
• given an additional class if dialogClass option is provided, for theme scoping
• wrap all overlay-related elements, such as ui-widget-overlay, ui-widget-shadow, ui-widget-stackfix (or whatever that bgiframe element will be called)