diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+# 0.4.0 (2017-07-13)
+    * Fixed a bug in the layout engine
+    * Dropped editorDefSetup
+    * Exposed the Layout primitives
 # 0.3.0 (2017-07-13)
     * Version bump required to comply with the Haskell PvP, as the recent layout changes
       were breaking changes due to deleted constructors.
diff --git a/examples/Person.hs b/examples/Person.hs
--- a/examples/Person.hs
+++ b/examples/Person.hs
@@ -12,7 +12,7 @@
 import qualified Generics.SOP                    as SOP
 import           GHC.Generics
 import           Graphics.UI.Threepenny.Core
-import           Graphics.UI.Threepenny.Editors
+import           Graphics.UI.Threepenny.Editors hiding (Single)
 import           Graphics.UI.Threepenny.Elements
 
 main :: IO ()
@@ -47,7 +47,7 @@
     let selector x = case x of
             Other _ -> "Other"
             _       -> show x
-    editorSum
+    editorSum horizontal
       [ ("Basic", const Basic <$> editorUnit)
       , ("Intermediate", const Intermediate <$> editorUnit)
       , ("Other", dimap (fromMaybe "" . getOther) Other editor)
diff --git a/src/Graphics/UI/Threepenny/Editors.hs b/src/Graphics/UI/Threepenny/Editors.hs
--- a/src/Graphics/UI/Threepenny/Editors.hs
+++ b/src/Graphics/UI/Threepenny/Editors.hs
@@ -24,6 +24,10 @@
     -- ** Generic editors
   , editorGeneric
   , editorGenericSimple
+    -- ** Layouts
+  , Layout(Grid, Single)
+  , horizontal
+  , vertical
   )where
 
 import Graphics.UI.Threepenny.Editors.Profunctor
diff --git a/src/Graphics/UI/Threepenny/Editors/Base.hs b/src/Graphics/UI/Threepenny/Editors/Base.hs
--- a/src/Graphics/UI/Threepenny/Editors/Base.hs
+++ b/src/Graphics/UI/Threepenny/Editors/Base.hs
@@ -15,9 +15,10 @@
     -- ** Editor definitions
   , EditorDef(..)
   , runEditorDef
-  , liftEditorDef
     -- ** Layouts
   , Layout(Grid, Single)
+  , horizontal
+  , vertical
     -- ** Editor composition
   , (|*|), (|*), (*|)
   , (-*-), (-*), (*-)
@@ -62,7 +63,7 @@
   getElement = editorElement
 
 newtype Layout
-  = Grid (Seq (Seq (Maybe Element)))-- ^ A non empty list of rows, where all the rows are assumed to have the same length
+  = Grid (Seq (Seq (Maybe Element))) -- ^ A non empty list of rows, where all the rows are assumed to have the same length
 
 pattern Single :: Element -> Layout
 pattern Single x <- Grid (Singleton (Singleton (Just x))) where Single x = Grid [[Just x]]
@@ -74,16 +75,19 @@
 vertical (Grid rows@(length.head.toList -> l1)) (Grid rows'@(length.head.toList -> l2)) =
     Grid $ fmap pad1 rows <> fmap pad2 rows'
   where
-    pad l1 l2 | l1 >= l2   = id
+    pad l1 l2 | l1 >= l2  = id
               | otherwise = (<> Seq.replicate (l2-l1) Nothing)
     pad1 = pad l1 l2
     pad2 = pad l2 l1
 
-horizontal (Grid rows@(length.head.toList -> l1)) (Grid rows'@(length.head.toList -> l2)) =
-    Grid $ Seq.zipWith (<>) (pad1 rows) (pad2 rows')
+horizontal (Grid rows@(length -> l1)) (Grid rows'@(length -> l2)) =
+  Grid $ Seq.zipWith (<>) (pad1 rows) (pad2 rows')
   where
-    pad l1 l2 | l1 >= l2 = id
-              | otherwise = \x -> let padding = Seq.replicate (length $ head $ toList x) Nothing in x <> Seq.replicate (l2-l1) padding
+    pad l1 l2
+      | l1 >= l2  = id
+      | otherwise = \x ->
+          let padding = Seq.replicate (length $ head $ toList x) Nothing
+          in x <> Seq.replicate (l2 - l1) padding
     pad1 = pad l1 l2
     pad2 = pad l2 l1
 
@@ -93,24 +97,17 @@
 data EditorDef a = EditorDef
   { editorDefTidings :: Tidings a
   , editorDefLayout  :: Layout
-  , editorDefSetup   :: UI Element -> UI Element
   }
   deriving Functor
 
-editorDef :: Tidings a -> Layout -> EditorDef a
-editorDef tidings layout = EditorDef tidings layout id
-
 editedDef :: EditorDef a -> Event a
 editedDef = rumors . editorDefTidings
 
 runEditorDef :: EditorDef a -> UI (Editor a)
 runEditorDef def = do
-  el <- runLayout (editorDefLayout def) # editorDefSetup def
+  el <- runLayout (editorDefLayout def) 
   return $ Editor (editorDefTidings def) el
 
-liftEditorDef :: (UI Element -> UI Element) -> EditorDef a -> EditorDef a
-liftEditorDef f def = def{editorDefSetup = f . editorDefSetup def }
-
 -- | The class of Editable datatypes.
 class Editable a where
   -- | The editor factory
@@ -125,7 +122,7 @@
   a <- getCompose a
   b <- getCompose b
   let ab = horizontal (editorDefLayout a) (editorDefLayout b)
-  return $ editorDef (editorDefTidings a <*> editorDefTidings b) ab
+  return $ EditorDef (editorDefTidings a <*> editorDefTidings b) ab
 
 -- | Left-right composition of an element with a editor
 (*|) :: UI Element -> Compose UI EditorDef a -> Compose UI EditorDef a
@@ -133,7 +130,7 @@
   e <- e
   a <- getCompose a
   let ea = horizontal (Single e) (editorDefLayout a)
-  return $ editorDef (editorDefTidings a) ea
+  return $ EditorDef (editorDefTidings a) ea
 
 -- | Left-right composition of an element with a editor
 (|*) :: Compose UI EditorDef a -> UI Element -> Compose UI EditorDef a
@@ -141,7 +138,7 @@
   e <- e
   a <- getCompose a
   let ea = horizontal (editorDefLayout a) (Single e)
-  return $ editorDef (editorDefTidings a) ea
+  return $ EditorDef (editorDefTidings a) ea
 
 -- | Top-down editor composition
 (-*-) :: Compose UI EditorDef (b -> a) -> Compose UI EditorDef b -> Compose UI EditorDef a
@@ -149,7 +146,7 @@
   a <- getCompose a
   b <- getCompose b
   let ab = vertical (editorDefLayout a) (editorDefLayout b)
-  return $ editorDef (editorDefTidings a <*> editorDefTidings b) ab
+  return $ EditorDef (editorDefTidings a <*> editorDefTidings b) ab
 
 -- | Top-down composition of an element with a editor
 (*-) :: UI Element -> Compose UI EditorDef a -> Compose UI EditorDef a
@@ -157,7 +154,7 @@
   e <- e
   a <- getCompose a
   let ea = vertical (Single e) (editorDefLayout a)
-  return $ editorDef (editorDefTidings a) ea
+  return $ EditorDef (editorDefTidings a) ea
 
 -- | Top-down composition of an element with a editor
 (-*) :: Compose UI EditorDef a -> UI Element -> Compose UI EditorDef a
@@ -165,7 +162,7 @@
   e <- e
   a <- getCompose a
   let ea = vertical (editorDefLayout a) (Single e)
-  return $ editorDef (editorDefTidings a) ea
+  return $ EditorDef (editorDefTidings a) ea
 
 editorReadShow :: (Read a, Show a) => Behavior (Maybe a) -> Compose UI EditorDef (Maybe a)
 editorReadShow b = Compose $ do
@@ -173,7 +170,7 @@
     let readIt "" = Nothing
         readIt x  = readMaybe x
     let t = tidings b (readIt <$> editedDef e)
-    return $ editorDef t (editorDefLayout e)
+    return $ EditorDef t (editorDefLayout e)
 
 -- An editor that presents a choice of values.
 editorEnumBounded
@@ -187,7 +184,7 @@
   => Behavior [a] -> Behavior(a -> UI Element) -> Behavior (Maybe a) -> Compose UI EditorDef (Maybe a)
 editorSelection options display b = Compose $ do
   l <- listBox options b display
-  return $ editorDef (tidings b (rumors $ userSelection l)) (Single $ getElement l)
+  return $ EditorDef (tidings b (rumors $ userSelection l)) (Single $ getElement l)
 
 -- | Ignores 'Nothing' values and only updates for 'Just' values
 editorJust :: (Behavior (Maybe b) -> Compose UI EditorDef (Maybe b))
@@ -196,13 +193,13 @@
 editorJust editor b = Compose $ do
   e <- getCompose $ editor (Just <$> b)
   let ev = filterJust (editedDef e)
-  return $ editorDef (tidings b ev) (editorDefLayout e)
+  return $ EditorDef (tidings b ev) (editorDefLayout e)
 
 -- | An editor for union types, built from editors for its constructors.
 editorSum
   :: (Ord tag, Show tag)
-  => [(tag, Compose UI EditorDef a)] -> (a -> tag) -> Behavior a -> Compose UI EditorDef a
-editorSum options selector ba = Compose $ do
+  => (Layout -> Layout -> Layout) -> [(tag, Compose UI EditorDef a)] -> (a -> tag) -> Behavior a -> Compose UI EditorDef a
+editorSum combineLayout options selector ba = Compose $ do
   options <- mapM (\(tag, Compose mk) -> (tag,) <$> (mk >>= runEditorDef)) options
   let tag = selector <$> ba
   tag' <- calmB tag
@@ -213,14 +210,14 @@
   nestedEditorDef <-
     new # sink children ((\x -> [maybe (error "editorSum") editorElement (build x)]) <$> tag')
   --
-  let composed = vertical (Single (getElement l)) (Single nestedEditorDef)
+  let composed = combineLayout (Single (getElement l)) (Single nestedEditorDef)
   -- the result event fires when any of the nested editors or the tag selector fire.
   let editedEvents = fmap (edited . snd) options
       eTag = filterJust $ rumors (userSelection l)
       taggedOptions = sequenceA [(tag, ) <$> contents e | (tag, e) <- options]
       editedTag = filterJust $ flip lookup <$> taggedOptions <@> eTag
       editedE = head <$> unions (editedTag : editedEvents)
-  return $ editorDef (tidings ba editedE) composed
+  return $ EditorDef (tidings ba editedE) composed
 
 -- | Returns a new behavior that only notifies for new values.
 calmB :: Eq a => Behavior a -> UI (Behavior a)
@@ -252,7 +249,7 @@
 instance Editable () where
   editor b = Compose $ do
     t <- new
-    return $ editorDef (tidings b never) (Single t)
+    return $ EditorDef (tidings b never) (Single t)
 
 instance a ~ Char => Editable [a] where
   editor b = Compose $ do
@@ -262,12 +259,12 @@
       initialValue <- currentValue b
       _ <- runUI w $ set value initialValue (element t)
       return ()
-    return $ editorDef (userText t) (Single $ getElement t)
+    return $ EditorDef (userText t) (Single $ getElement t)
 
 instance Editable Bool where
   editor b = Compose $ do
     t <- sink checked b $ input # set type_ "checkbox"
-    return $ editorDef (tidings b $ checkedChange t) (Single t)
+    return $ EditorDef (tidings b $ checkedChange t) (Single t)
 
 instance Editable (Maybe Int) where editor = editorReadShow
 instance Editable (Maybe Double) where editor = editorReadShow
diff --git a/src/Graphics/UI/Threepenny/Editors/Profunctor.hs b/src/Graphics/UI/Threepenny/Editors/Profunctor.hs
--- a/src/Graphics/UI/Threepenny/Editors/Profunctor.hs
+++ b/src/Graphics/UI/Threepenny/Editors/Profunctor.hs
@@ -22,7 +22,6 @@
   , Base.contents
   , EditorFactory(..)
   , createEditor
-  , liftEditor
   , Editable(..)
     -- ** Editor composition
   , (|*|), (|*), (*|)
@@ -41,6 +40,10 @@
     -- ** Generic editors
   , editorGeneric
   , editorGenericSimple
+    -- ** Layouts
+  , Base.Layout(Grid, Single)
+  , Base.horizontal
+  , Base.vertical
   )where
 
 import           Data.Bifunctor
@@ -61,11 +64,6 @@
   { run :: Behavior a -> Compose UI Base.EditorDef b
   }
 
-liftEditor :: (UI Element -> UI Element) -> EditorFactory a b -> EditorFactory a b
-liftEditor f (EditorFactory run) = EditorFactory $ \b ->
-  case run b of
-    Compose uidef -> Compose $ fmap (Base.liftEditorDef f) uidef
-
 -- | Create an editor to display the argument.
 --   User edits are fed back via the 'edited' 'Event'.
 createEditor :: EditorFactory b a -> Behavior b -> UI (Base.Editor a)
@@ -139,10 +137,10 @@
 -- | An editor for union types, built from editors for its constructors.
 editorSum
   :: (Show tag, Ord tag)
-  => [(tag, EditorFactory b b)] -> (b -> tag) -> EditorFactory b b
-editorSum nested tagger = EditorFactory $ \b ->
+  => (Base.Layout -> Base.Layout -> Base.Layout) -> [(tag, EditorFactory b b)] -> (b -> tag) -> EditorFactory b b
+editorSum layout nested tagger = EditorFactory $ \b ->
   let nested' = [ (tag, run f b) | (tag, f) <- nested ]
-  in Base.editorSum nested' tagger b
+  in Base.editorSum layout nested' tagger b
 
 instance Editable () where editor = EditorFactory Base.editor
 instance Editable String where editor = EditorFactory Base.editor
@@ -198,7 +196,7 @@
      (All (All Editable `And` All Default) xx)
   => DatatypeInfo xx -> EditorFactory (SOP I xx) (SOP I xx)
 editorGeneric' (ADT _ _ (c :* Nil)) = constructorEditorFor c
-editorGeneric' (ADT _ _ cc) = editorSum editors constructor where
+editorGeneric' (ADT _ _ cc) = editorSum Base.vertical editors constructor where
   editors :: [(Tag, EditorFactory (SOP I xx) (SOP I xx))]
   editors = map (first Tag) $ constructorEditorsFor cc
   constructors = hmap (K . constructorName) cc
diff --git a/threepenny-editors.cabal b/threepenny-editors.cabal
--- a/threepenny-editors.cabal
+++ b/threepenny-editors.cabal
@@ -3,7 +3,7 @@
 -- see: https://github.com/sol/hpack
 
 name:           threepenny-editors
-version:        0.3.0
+version:        0.4.0
 synopsis:       Composable algebraic editors
 description:    This package provides a type class 'Editable' and combinators to
                 easily put together form-like editors for algebraic datatypes.