Hi Malalai,
In the case of right-to-left languages I would add a client variable to store if the locale is RTL or not (set when the locale is changed), add a CSS class for RTL, and in those cases append that class to a widget that is high on the hierarchy (e.g. on the LayoutWrapper container on LayoutTopMenu):

Hope this helps.
Cheers,
Tiago Simões