diff --git a/output/src/layout.rs b/output/src/layout.rs
index 14f1cef..57eb080 100644
--- a/output/src/layout.rs
+++ b/output/src/layout.rs
@@ -507,6 +507,303 @@ transform_xy_unit!("padding/x" "padding/y" "padding/xy"|self: Padding, area|{
         "y"  => Self::y(tail(0)?, tail(1)?),
         "xy" => Self::xy(tail(0)?, tail(1)?, tail(2)?),
         _ => return Err("invalid max variant".into()) });
+}
+
+/// Lazily-evaluated [Render]able.
+pub struct Thunk<E: Output, T: Render<E>, F: Fn()->T>(
+    PhantomData<E>,
+    F
+);
+impl<E: Output, T: Render<E>, F: Fn()->T> Thunk<E, T, F> {
+    pub const fn new (thunk: F) -> Self {
+        Self(PhantomData, thunk)
+    }
+}
+impl<E: Output, T: Render<E>, F: Fn()->T> Content<E> for Thunk<E, T, F> {
+    fn content (&self) -> impl Render<E> { (self.1)() }
+}
+
+pub struct ThunkBox<E: Output>(
+    PhantomData<E>,
+    Box<dyn Fn()->Box<dyn Render<E>>>,
+);
+impl<E: Output> ThunkBox<E> {
+    pub const fn new (thunk: Box<dyn Fn()->Box<dyn Render<E>>>) -> Self {
+        Self(PhantomData, thunk)
+    }
+}
+impl<E: Output> Content<E> for ThunkBox<E> {
+    fn content (&self) -> impl Render<E> { (&self.1)() }
+}
+impl<E: Output> From<Box<dyn Fn()->Box<dyn Render<E>>>> for ThunkBox<E> {
+    fn from (f: Box<dyn Fn()->Box<dyn Render<E>>>) -> Self {
+        Self(PhantomData, f)
+    }
+}
+//impl<'a, E: Output, F: Fn()->Box<dyn Render<E> + 'a> + 'a> From<F> for ThunkBox<'a, E> {
+    //fn from (f: F) -> Self {
+        //Self(Default::default(), Box::new(f))
+    //}
+//}
+
+pub struct ThunkRender<E: Output, F: Fn(&mut E)>(PhantomData<E>, F);
+impl<E: Output, F: Fn(&mut E)> ThunkRender<E, F> {
+    pub fn new (render: F) -> Self { Self(PhantomData, render) }
+}
+impl<E: Output, F: Fn(&mut E)> Content<E> for ThunkRender<E, F> {
+    fn render (&self, to: &mut E) { (self.1)(to) }
+}
+
+pub struct ThunkLayout<
+    E: Output,
+    F1: Fn(E::Area)->E::Area, 
+    F2: Fn(&mut E)
+>(
+    PhantomData<E>, 
+    F1,
+    F2
+);
+impl<E: Output, F1: Fn(E::Area)->E::Area, F2: Fn(&mut E)> ThunkLayout<E, F1, F2> {
+    pub fn new (layout: F1, render: F2) -> Self { Self(PhantomData, layout, render) }
+}
+impl<E, F1, F2> Content<E> for ThunkLayout<E, F1, F2>
+where
+    E:  Output,
+    F1: Fn(E::Area)->E::Area,
+    F2: Fn(&mut E)
+{
+    fn layout (&self, to: E::Area) -> E::Area { (self.1)(to) }
+    fn render (&self, to: &mut E) { (self.2)(to) }
+}
+
+#[derive(Debug, Default)] pub struct Memo<T, U> {
+    pub value: T,
+    pub view: Arc<RwLock<U>>
+}
+
+impl<T: PartialEq, U> Memo<T, U> {
+    pub fn new (value: T, view: U) -> Self {
+        Self { value, view: Arc::new(view.into()) }
+    }
+    pub fn update <R> (
+        &mut self,
+        newval: T,
+        render: impl Fn(&mut U, &T, &T)->R
+    ) -> Option<R> {
+        if newval != self.value {
+            let result = render(&mut*self.view.write().unwrap(), &newval, &self.value);
+            self.value = newval;
+            return Some(result);
+        }
+        None
+    }
+}
+
+/// Clear a pre-allocated buffer, then write into it.
+#[macro_export] macro_rules! rewrite {
+    ($buf:ident, $($rest:tt)*) => { |$buf,_,_|{ $buf.clear(); write!($buf, $($rest)*) } }
+}
+
+pub struct Stack<'t, E, F1> {
+    __:        PhantomData<&'t (E, F1)>,
+    direction: Direction,
+    callback:  F1
+}
+impl<'t, 'u: 't, E, F1> Stack<'t, E, F1> where
+    Self: 't, E: Output, F1: Fn(&mut dyn FnMut(&dyn Render<E>)) + Send + Sync,
+{
+    pub fn north (callback: F1) -> Self { Self::new(North, callback) }
+    pub fn south (callback: F1) -> Self { Self::new(South, callback) }
+    pub fn east  (callback: F1) -> Self { Self::new(East, callback)  }
+    pub fn west  (callback: F1) -> Self { Self::new(West, callback)  }
+    pub fn above (callback: F1) -> Self { Self::new(Above, callback) }
+    pub fn below (callback: F1) -> Self { Self::new(Below, callback) }
+    pub fn new (direction: Direction, callback: F1) -> Self {
+        Self { direction, callback, __: Default::default(), }
+    }
+}
+impl<'t, 'u, E, F1> Content<E> for Stack<'t, E, F1> where
+    Self: 't, E: Output, F1: Fn(&mut dyn FnMut(&dyn Render<E>)) + Send + Sync,
+{
+    fn layout (&self, to: E::Area) -> E::Area {
+        let Self { direction, callback, .. } = self;
+        let (mut x, mut y) = (to.x(), to.y());
+        let (mut w_used, mut w_remaining) = (E::Unit::zero(), to.w());
+        let (mut h_used, mut h_remaining) = (E::Unit::zero(), to.h());
+        callback(&mut move|component: &dyn Render<E>|{
+            let [_, _, w, h] = component.layout([x, y, w_remaining, h_remaining].into()).xywh();
+            match direction {
+                South => { y           = y.plus(h);
+                           h_used      = h_used.plus(h);
+                           h_remaining = h_remaining.minus(h);
+                           w_used      = w_used.max(w); },
+                East  => { x           = x.plus(w);
+                           w_used      = w_used.plus(w);
+                           w_remaining = w_remaining.minus(w);
+                           h_used      = h_used.max(h); },
+                North | West  => { todo!() },
+                Above | Below => {},
+            }
+        });
+        match direction {
+            North | West  => { todo!() },
+            South | East  => { [to.x(), to.y(), w_used.into(), h_used.into()].into() },
+            Above | Below => { [to.x(), to.y(), to.w(), to.h()].into() },
+        }
+    }
+    fn render (&self, to: &mut E) {
+        let Self { direction, callback, .. } = self;
+        let (mut x, mut y) = (to.x(), to.y());
+        let (mut w_used, mut w_remaining) = (E::Unit::zero(), to.w());
+        let (mut h_used, mut h_remaining) = (E::Unit::zero(), to.h());
+        callback(&mut move|component: &dyn Render<E>|{
+            let layout = component.layout([x, y, w_remaining, h_remaining].into());
+            match direction {
+                South => {
+                    y           = y.plus(layout.h());
+                    h_remaining = h_remaining.minus(layout.h());
+                    h_used      = h_used.plus(layout.h()) },
+                East  => {
+                    x           = x.plus(layout.w());
+                    w_remaining = w_remaining.minus(layout.w());
+                    w_used      = w_used.plus(layout.h()) },
+                North | West  => { todo!() },
+                Above | Below => {}
+            };
+            to.place(layout, component);
+        });
+    }
+}
+
+/// Renders items from an iterator.
+pub struct Map<E, A, B, I, F, G>
+where
+    I: Iterator<Item = A> + Send + Sync,
+    F: Fn() -> I + Send + Sync,
+{
+    __: PhantomData<(E, B)>,
+    /// Function that returns iterator over stacked components
+    get_iter: F,
+    /// Function that returns each stacked component
+    get_item: G,
+}
+
+impl<'a, E, A, B, I, F, G> Map<E, A, B, I, F, G> where
+    I: Iterator<Item = A> + Send + Sync + 'a,
+    F: Fn() -> I + Send + Sync + 'a,
+{
+    pub const fn new (get_iter: F, get_item: G) -> Self {
+        Self {
+            __: PhantomData,
+            get_iter,
+            get_item
+        }
+    }
+}
+
+macro_rules! impl_map_direction (($name:ident, $axis:ident, $align:ident)=>{
+    impl<'a, E, A, B, I, F> Map<
+        E, A, Push<E::Unit, Align<Fixed<E::Unit, Fill<B>>>>, I, F, fn(A, usize)->B
+    > where
+        E: Output,
+        B: Render<E>,
+        I: Iterator<Item = A> + Send + Sync + 'a,
+        F: Fn() -> I + Send + Sync + 'a
+    {
+        pub const fn $name (
+            size:     E::Unit,
+            get_iter: F,
+            get_item: impl Fn(A, usize)->B + Send + Sync
+        ) -> Map<
+            E, A,
+            Push<E::Unit, Align<Fixed<E::Unit, B>>>,
+            I, F,
+            impl Fn(A, usize)->Push<E::Unit, Align<Fixed<E::Unit, B>>> + Send + Sync
+        > {
+            Map {
+                __: PhantomData,
+                get_iter,
+                get_item: move |item: A, index: usize|{
+                    // FIXME: multiply
+                    let mut push: E::Unit = E::Unit::from(0u16);
+                    for _ in 0..index {
+                        push = push + size;
+                    }
+                    Push::$axis(push, Align::$align(Fixed::$axis(size, get_item(item, index))))
+                }
+            }
+        }
+    }
+});
+
+impl_map_direction!(east,  x, w);
+impl_map_direction!(south, y, n);
+impl_map_direction!(west,  x, e);
+impl_map_direction!(north, y, s);
+
+impl<'a, E, A, B, I, F, G> Content<E> for Map<E, A, B, I, F, G> where
+    E: Output,
+    B: Render<E>,
+    I: Iterator<Item = A> + Send + Sync + 'a,
+    F: Fn() -> I + Send + Sync + 'a,
+    G: Fn(A, usize)->B + Send + Sync
+{
+    fn layout (&self, area: E::Area) -> E::Area {
+        let Self { get_iter, get_item, .. } = self;
+        let mut index = 0;
+        let [mut min_x, mut min_y] = area.center();
+        let [mut max_x, mut max_y] = area.center();
+        for item in get_iter() {
+            let [x,y,w,h] = get_item(item, index).layout(area).xywh();
+            min_x = min_x.min(x.into());
+            min_y = min_y.min(y.into());
+            max_x = max_x.max((x + w).into());
+            max_y = max_y.max((y + h).into());
+            index += 1;
+        }
+        let w = max_x - min_x;
+        let h = max_y - min_y;
+        //[min_x.into(), min_y.into(), w.into(), h.into()].into()
+        area.center_xy([w.into(), h.into()].into()).into()
+    }
+    fn render (&self, to: &mut E) {
+        let Self { get_iter, get_item, .. } = self;
+        let mut index = 0;
+        let area = Content::layout(self, to.area());
+        for item in get_iter() {
+            let item = get_item(item, index);
+            //to.place(area.into(), &item);
+            to.place(item.layout(area), &item);
+            index += 1;
+        }
+    }
+}
+
+#[inline] pub fn map_south<O: Output>(
+    item_offset: O::Unit,
+    item_height: O::Unit,
+    item: impl Content<O>
+) -> impl Content<O> {
+    Push::y(item_offset, Fixed::y(item_height, Fill::x(item)))
+}
+
+#[inline] pub fn map_south_west<O: Output>(
+    item_offset: O::Unit,
+    item_height: O::Unit,
+    item: impl Content<O>
+) -> impl Content<O> {
+    Push::y(item_offset, Align::nw(Fixed::y(item_height, Fill::x(item))))
+}
+
+#[inline] pub fn map_east<O: Output>(
+    item_offset: O::Unit,
+    item_width:  O::Unit,
+    item: impl Content<O>
+) -> impl Content<O> {
+    Push::x(item_offset, Align::w(Fixed::x(item_width, Fill::y(item))))
+}
+
+///////////////////////////////////////////////////////////////////////////////
 
 
     ///// The syntagm `(when :condition :content)` corresponds to a [When] layout element.
@@ -674,176 +971,6 @@ transform_xy_unit!("padding/x" "padding/y" "padding/xy"|self: Padding, area|{
                 //)),
                 //_ => None
             //})
-}
-
-/// Lazily-evaluated [Render]able.
-pub struct Thunk<E: Output, T: Render<E>, F: Fn()->T>(
-    PhantomData<E>,
-    F
-);
-impl<E: Output, T: Render<E>, F: Fn()->T> Thunk<E, T, F> {
-    pub const fn new (thunk: F) -> Self {
-        Self(PhantomData, thunk)
-    }
-}
-impl<E: Output, T: Render<E>, F: Fn()->T> Content<E> for Thunk<E, T, F> {
-    fn content (&self) -> impl Render<E> { (self.1)() }
-}
-
-pub struct ThunkBox<E: Output>(
-    PhantomData<E>,
-    Box<dyn Fn()->Box<dyn Render<E>>>,
-);
-impl<E: Output> ThunkBox<E> {
-    pub const fn new (thunk: Box<dyn Fn()->Box<dyn Render<E>>>) -> Self {
-        Self(PhantomData, thunk)
-    }
-}
-impl<E: Output> Content<E> for ThunkBox<E> {
-    fn content (&self) -> impl Render<E> { (&self.1)() }
-}
-impl<E: Output> From<Box<dyn Fn()->Box<dyn Render<E>>>> for ThunkBox<E> {
-    fn from (f: Box<dyn Fn()->Box<dyn Render<E>>>) -> Self {
-        Self(PhantomData, f)
-    }
-}
-//impl<'a, E: Output, F: Fn()->Box<dyn Render<E> + 'a> + 'a> From<F> for ThunkBox<'a, E> {
-    //fn from (f: F) -> Self {
-        //Self(Default::default(), Box::new(f))
-    //}
-//}
-
-pub struct ThunkRender<E: Output, F: Fn(&mut E)>(PhantomData<E>, F);
-impl<E: Output, F: Fn(&mut E)> ThunkRender<E, F> {
-    pub fn new (render: F) -> Self { Self(PhantomData, render) }
-}
-impl<E: Output, F: Fn(&mut E)> Content<E> for ThunkRender<E, F> {
-    fn render (&self, to: &mut E) { (self.1)(to) }
-}
-
-pub struct ThunkLayout<
-    E: Output,
-    F1: Fn(E::Area)->E::Area, 
-    F2: Fn(&mut E)
->(
-    PhantomData<E>, 
-    F1,
-    F2
-);
-impl<E: Output, F1: Fn(E::Area)->E::Area, F2: Fn(&mut E)> ThunkLayout<E, F1, F2> {
-    pub fn new (layout: F1, render: F2) -> Self { Self(PhantomData, layout, render) }
-}
-impl<E, F1, F2> Content<E> for ThunkLayout<E, F1, F2>
-where
-    E:  Output,
-    F1: Fn(E::Area)->E::Area,
-    F2: Fn(&mut E)
-{
-    fn layout (&self, to: E::Area) -> E::Area { (self.1)(to) }
-    fn render (&self, to: &mut E) { (self.2)(to) }
-}
-
-#[derive(Debug, Default)] pub struct Memo<T, U> {
-    pub value: T,
-    pub view: Arc<RwLock<U>>
-}
-
-impl<T: PartialEq, U> Memo<T, U> {
-    pub fn new (value: T, view: U) -> Self {
-        Self { value, view: Arc::new(view.into()) }
-    }
-    pub fn update <R> (
-        &mut self,
-        newval: T,
-        render: impl Fn(&mut U, &T, &T)->R
-    ) -> Option<R> {
-        if newval != self.value {
-            let result = render(&mut*self.view.write().unwrap(), &newval, &self.value);
-            self.value = newval;
-            return Some(result);
-        }
-        None
-    }
-}
-
-/// Clear a pre-allocated buffer, then write into it.
-#[macro_export] macro_rules! rewrite {
-    ($buf:ident, $($rest:tt)*) => { |$buf,_,_|{ $buf.clear(); write!($buf, $($rest)*) } }
-}
-
-pub struct Stack<'t, E, F1> {
-    __: PhantomData<&'t (E, F1)>,
-    direction: Direction,
-    callback:  F1
-}
-impl<'t, E, F1> Stack<'t, E, F1> where
-    E: Output,
-    F1: Fn(&mut dyn FnMut(&(dyn Render<E> + 't))) + Send + Sync,
-{
-    pub fn north (callback: F1) -> Self { Self::new(North, callback) }
-    pub fn south (callback: F1) -> Self { Self::new(South, callback) }
-    pub fn east  (callback: F1) -> Self { Self::new(East, callback)  }
-    pub fn west  (callback: F1) -> Self { Self::new(West, callback)  }
-    pub fn above (callback: F1) -> Self { Self::new(Above, callback) }
-    pub fn below (callback: F1) -> Self { Self::new(Below, callback) }
-    pub fn new (direction: Direction, callback: F1) -> Self {
-        Self { direction, callback, __: Default::default(), }
-    }
-}
-impl<'t, E, F1> Content<E> for Stack<'t, E, F1> where
-    Self: 't,
-    E: Output,
-    F1: Fn(&mut dyn FnMut(&(dyn Render<E> + 't))) + Send + Sync,
-{
-    fn layout (&self, to: E::Area) -> E::Area {
-        let Self { direction, callback, .. } = self;
-        let (mut x, mut y) = (to.x(), to.y());
-        let (mut w_used, mut w_remaining) = (E::Unit::zero(), to.w());
-        let (mut h_used, mut h_remaining) = (E::Unit::zero(), to.h());
-        callback(&mut move|component|{
-            let [_, _, w, h] = component.layout([x, y, w_remaining, h_remaining].into()).xywh();
-            match direction {
-                South => { y           = y.plus(h);
-                           h_used      = h_used.plus(h);
-                           h_remaining = h_remaining.minus(h);
-                           w_used      = w_used.max(w); },
-                East  => { x           = x.plus(w);
-                           w_used      = w_used.plus(w);
-                           w_remaining = w_remaining.minus(w);
-                           h_used      = h_used.max(h); },
-                North | West  => { todo!() },
-                Above | Below => {},
-            }
-        });
-        match direction {
-            North | West  => { todo!() },
-            South | East  => { [to.x(), to.y(), w_used.into(), h_used.into()].into() },
-            Above | Below => { [to.x(), to.y(), to.w(), to.h()].into() },
-        }
-    }
-    fn render (&self, to: &mut E) {
-        let Self { direction, callback, .. } = self;
-        let (mut x, mut y) = (to.x(), to.y());
-        let (mut w_used, mut w_remaining) = (E::Unit::zero(), to.w());
-        let (mut h_used, mut h_remaining) = (E::Unit::zero(), to.h());
-        callback(&mut move|component|{
-            let layout = component.layout([x, y, w_remaining, h_remaining].into());
-            match direction {
-                South => {
-                    y           = y.plus(layout.h());
-                    h_remaining = h_remaining.minus(layout.h());
-                    h_used      = h_used.plus(layout.h()) },
-                East  => {
-                    x           = x.plus(layout.w());
-                    w_remaining = w_remaining.minus(layout.w());
-                    w_used      = w_used.plus(layout.h()) },
-                North | West  => { todo!() },
-                Above | Below => {}
-            };
-            to.place(layout, component);
-        });
-    }
-}
 
 /*Stack::down(|add|{
     let mut i = 0;
@@ -862,131 +989,3 @@ impl<'t, E, F1> Content<E> for Stack<'t, E, F1> where
     add(&format!("{}/{i}", self.index))?;
     Ok(())
 }));*/
-
-/// Renders items from an iterator.
-pub struct Map<E, A, B, I, F, G>
-where
-    I: Iterator<Item = A> + Send + Sync,
-    F: Fn() -> I + Send + Sync,
-{
-    __: PhantomData<(E, B)>,
-    /// Function that returns iterator over stacked components
-    get_iter: F,
-    /// Function that returns each stacked component
-    get_item: G,
-}
-
-impl<'a, E, A, B, I, F, G> Map<E, A, B, I, F, G> where
-    I: Iterator<Item = A> + Send + Sync + 'a,
-    F: Fn() -> I + Send + Sync + 'a,
-{
-    pub const fn new (get_iter: F, get_item: G) -> Self {
-        Self {
-            __: PhantomData,
-            get_iter,
-            get_item
-        }
-    }
-}
-
-macro_rules! impl_map_direction (($name:ident, $axis:ident, $align:ident)=>{
-    impl<'a, E, A, B, I, F> Map<
-        E, A, Push<E::Unit, Align<Fixed<E::Unit, Fill<B>>>>, I, F, fn(A, usize)->B
-    > where
-        E: Output,
-        B: Render<E>,
-        I: Iterator<Item = A> + Send + Sync + 'a,
-        F: Fn() -> I + Send + Sync + 'a
-    {
-        pub const fn $name (
-            size:     E::Unit,
-            get_iter: F,
-            get_item: impl Fn(A, usize)->B + Send + Sync
-        ) -> Map<
-            E, A,
-            Push<E::Unit, Align<Fixed<E::Unit, B>>>,
-            I, F,
-            impl Fn(A, usize)->Push<E::Unit, Align<Fixed<E::Unit, B>>> + Send + Sync
-        > {
-            Map {
-                __: PhantomData,
-                get_iter,
-                get_item: move |item: A, index: usize|{
-                    // FIXME: multiply
-                    let mut push: E::Unit = E::Unit::from(0u16);
-                    for _ in 0..index {
-                        push = push + size;
-                    }
-                    Push::$axis(push, Align::$align(Fixed::$axis(size, get_item(item, index))))
-                }
-            }
-        }
-    }
-});
-
-impl_map_direction!(east,  x, w);
-impl_map_direction!(south, y, n);
-impl_map_direction!(west,  x, e);
-impl_map_direction!(north, y, s);
-
-impl<'a, E, A, B, I, F, G> Content<E> for Map<E, A, B, I, F, G> where
-    E: Output,
-    B: Render<E>,
-    I: Iterator<Item = A> + Send + Sync + 'a,
-    F: Fn() -> I + Send + Sync + 'a,
-    G: Fn(A, usize)->B + Send + Sync
-{
-    fn layout (&self, area: E::Area) -> E::Area {
-        let Self { get_iter, get_item, .. } = self;
-        let mut index = 0;
-        let [mut min_x, mut min_y] = area.center();
-        let [mut max_x, mut max_y] = area.center();
-        for item in get_iter() {
-            let [x,y,w,h] = get_item(item, index).layout(area).xywh();
-            min_x = min_x.min(x.into());
-            min_y = min_y.min(y.into());
-            max_x = max_x.max((x + w).into());
-            max_y = max_y.max((y + h).into());
-            index += 1;
-        }
-        let w = max_x - min_x;
-        let h = max_y - min_y;
-        //[min_x.into(), min_y.into(), w.into(), h.into()].into()
-        area.center_xy([w.into(), h.into()].into()).into()
-    }
-    fn render (&self, to: &mut E) {
-        let Self { get_iter, get_item, .. } = self;
-        let mut index = 0;
-        let area = Content::layout(self, to.area());
-        for item in get_iter() {
-            let item = get_item(item, index);
-            //to.place(area.into(), &item);
-            to.place(item.layout(area), &item);
-            index += 1;
-        }
-    }
-}
-
-#[inline] pub fn map_south<O: Output>(
-    item_offset: O::Unit,
-    item_height: O::Unit,
-    item: impl Content<O>
-) -> impl Content<O> {
-    Push::y(item_offset, Fixed::y(item_height, Fill::x(item)))
-}
-
-#[inline] pub fn map_south_west<O: Output>(
-    item_offset: O::Unit,
-    item_height: O::Unit,
-    item: impl Content<O>
-) -> impl Content<O> {
-    Push::y(item_offset, Align::nw(Fixed::y(item_height, Fill::x(item))))
-}
-
-#[inline] pub fn map_east<O: Output>(
-    item_offset: O::Unit,
-    item_width:  O::Unit,
-    item: impl Content<O>
-) -> impl Content<O> {
-    Push::x(item_offset, Align::w(Fixed::x(item_width, Fill::y(item))))
-}