Prune commentary and stale Rust port notes

core/src/ui/mod.rs

@@ -18,20 +18,7 @@ pub struct UiData {
     pub textures: Textures,
     pub text: TextData,
     pub masks: TrackedArena<Mask, u32>,
-    /// One entry per widget ever drawn, plus optional child-coordinate
-    /// boundaries owned by containers. Together they form the parent-linked
-    /// chain `resolve_move` walks in both shader stages. A widget's ordinary
-    /// entry is allocated once on its first draw and reused for every later
-    /// redraw of the same id, so a retained descendant's `parent` index never
-    /// goes stale -- see LAYOUT.md section 2.
     pub move_offsets: TrackedArena<MoveOffset, u32>,
-    /// Every widget whose [`crate::Widget::tick`] should run before the
-    /// next frame -- today, a `LazySpan` coasting through a fling. Added by
-    /// [`Self::animate`] when the animation starts and removed by
-    /// [`Self::tick_animations`] the frame its `tick` answers `false`, so
-    /// a stopped animation costs nothing and a dropped widget cannot be
-    /// ticked (`get_dyn_mut` answers `None` and it is dropped the same
-    /// way).
     animating: Vec<WidgetId>,
 }
 
@@ -46,15 +33,7 @@ impl UiData {
         }
     }
 
-    /// Tick every registered widget to `now`, drop the ones that finished,
-    /// and say whether any is still going -- which is a backend's cue to
-    /// ask for another frame. Called once per frame *before* the draw, so
-    /// what the frame draws is this instant's position rather than the
-    /// previous one's.
     pub fn tick_animations(&mut self, now: std::time::Instant) -> bool {
-        // Taken out and put back rather than iterated in place: `tick`
-        // needs `&mut` on the widget arena this list lives beside, and a
-        // widget is free to register another one while ticking.
         let mut registered = std::mem::take(&mut self.animating);
         registered.retain(|&id| match self.widgets.get_dyn_mut(id) {
             Some(widget) => widget.tick(now),