@Aishwarya
I’m sorry for the late reply. Somehow I haven’t noticed this topic. 
Some widgets are still really missing from SLS because they require special handling. We are adding these gradually.
Speaking about the menu widget, I consider it a quite special and complex one (i.e. not too generic) and I think it’d be hard to use in UIs. Ideally it should be possible to easily create such a widget in SLS from scartch using layouts, events and components.
@chrisplex928
If you would like to extend the functionality of the UI you can do anything after calling ui_init(). So if you need to add some extra features for the roller (which are not supported in SLS) you can just do something like:
ui_init();
lv_roller_set_...(ui_Roller_1, ...);