comments

src/layout/painter.rs

@@ -183,6 +183,9 @@ impl<'a, Ctx> Painter<'a, Ctx> {
         }
     }
 
+    /// shifts the primitive spans for all widgets above this one in the tree
+    /// also goes into children of them and modifies those that come after this one
+    /// should be done after applying primitives to ensure active spans are correct
     fn shift_parent(&mut self, parent: Id, start: usize, delta: isize) {
         let instance = self.active.widgets.get_mut(&parent).unwrap();
         let end = &mut instance.span.end;