Hi Emre,
Sorry for the late reply,
I tried some other way but no Joy.
How do you mean sub categories? where would they go??
I Think as this is designed more towards touch screens I think what would be better is if at the top and bottom there was a up and down buttons
and as menu/departments loads it loads say 10 menu buttons it loads the first 10 then when the buttom arrow is clicked it loads the next 10 and so on, rather then a scroll bar come up as some menus can have to many titles such as pizzas, burgers etc and it can make it easy to follow for users.
Its just an idea of what I think, This is how i designed the access db that i used in my family business.