abuse macros..

src/widget/position/span.rs

@@ -151,7 +151,7 @@ pub struct SpanBuilder<State, const LEN: usize, Wa: WidgetArrLike<State, LEN, Ta
     _pd: PhantomData<(State, Tag)>,
 }
 
-impl<State, const LEN: usize, Wa: WidgetArrLike<State, LEN, Tag>, Tag> FnOnce<(&mut State,)>
+impl<State: StateLike<State>, const LEN: usize, Wa: WidgetArrLike<State, LEN, Tag>, Tag> FnOnce<(&mut State,)>
     for SpanBuilder<State, LEN, Wa, Tag>
 {
     type Output = Span;

src/widget/position/stack.rs

@@ -48,7 +48,7 @@ pub struct StackBuilder<State, const LEN: usize, Wa: WidgetArrLike<State, LEN, T
     _pd: PhantomData<(State, Tag)>,
 }
 
-impl<State, const LEN: usize, Wa: WidgetArrLike<State, LEN, Tag>, Tag> FnOnce<(&mut State,)>
+impl<State: StateLike<State>, const LEN: usize, Wa: WidgetArrLike<State, LEN, Tag>, Tag> FnOnce<(&mut State,)>
     for StackBuilder<State, LEN, Wa, Tag>
 {
     type Output = Stack;