Function compose_frame 

pub fn compose_frame<F>(
    sched: &mut Scheduler,
    root_fn: &mut F,
    scale: f32,
    size_px_u32: (u32, u32),
    hover_id: Option<u64>,
    pressed_ids: &HashSet<u64>,
    tf_states: &HashMap<u64, Rc<RefCell<TextFieldState>>>,
    focused: Option<u64>,
) -> Frame
where
    F: FnMut(&mut Scheduler) -> View,

Compose a single frame with density and text-scale applied, returning Frame.