diff --git a/fltkhs.cabal b/fltkhs.cabal
--- a/fltkhs.cabal
+++ b/fltkhs.cabal
@@ -1,5 +1,5 @@
 name : fltkhs
-version : 0.8.0.0
+version : 0.8.0.1
 synopsis : FLTK bindings
 description: Low level bindings for the FLTK GUI toolkit. For installation and quick start instruction please scroll all the way down to the README.
 license : MIT
diff --git a/scripts/doc-parser.hs b/scripts/doc-parser.hs
--- a/scripts/doc-parser.hs
+++ b/scripts/doc-parser.hs
@@ -149,7 +149,7 @@
 word = manyTill anyChar (try (string " "))
 
 isWidget w ((_,_),_,w') = w == w'
-data Command = Functions String | Hierarchy String | Sync
+data Command = Functions String | Hierarchy String | Sync | CheckHierarchies
 
 traceHierarchy :: String -> [String] -> [(String,String)] -> [String]
 traceHierarchy w accum dict = case (lookup w dict) of
@@ -162,8 +162,9 @@
         case args of
           ("functions":w':[]) -> Just (Functions w')
           ("hierarchy":w':[]) -> Just (Hierarchy w')
-          ("sync":[])         -> Just Sync
-          _                   -> Nothing
+          ("sync":[]) -> Just Sync
+          ("checkHierarchies":[]) -> Just CheckHierarchies
+          _ -> Nothing
   hierarchyContents <- readFile "../src/Graphics/UI/FLTK/LowLevel/Hierarchy.hs"
   let objs = (
                filter (not . isInfixOf "Funcs") .
@@ -213,6 +214,18 @@
       let (functions, inNewVersionOnly) = parseWidgetFile contents
       let rendered = maybe [] (sort . map (\(c, sig, mName, wType) -> pprint ((c, sig), mName, wType)))
       putStr $ intercalate "\n--\n" (map ((++) "-- ") (rendered functions))
+    (Just CheckHierarchies) -> 
+      print
+        (foldl
+          (\badHierarchies (o,parentO) ->
+             maybe
+               badHierarchies
+               (\_ ->
+                 if (not (parentO == (o ++ "Base")))
+                 then badHierarchies ++ [o]
+                 else badHierarchies)
+               (lookup (o ++ "Base") hier'))
+           [] hier')
     (Just Sync) ->
       mapM
         (\(w,hierarchyFs) -> do
diff --git a/src/Graphics/UI/FLTK/LowLevel/Base/DoubleWindow.chs b/src/Graphics/UI/FLTK/LowLevel/Base/DoubleWindow.chs
--- a/src/Graphics/UI/FLTK/LowLevel/Base/DoubleWindow.chs
+++ b/src/Graphics/UI/FLTK/LowLevel/Base/DoubleWindow.chs
@@ -30,7 +30,6 @@
 import Graphics.UI.FLTK.LowLevel.Hierarchy
 import Graphics.UI.FLTK.LowLevel.Base.Widget
 import Graphics.UI.FLTK.LowLevel.Base.Window
-import Graphics.UI.FLTK.LowLevel.Window
 
 {# fun Fl_OverriddenDouble_Window_New as overriddenWindowNew' {`Int',`Int', id `Ptr ()'} -> `Ptr ()' id #}
 {# fun Fl_OverriddenDouble_Window_NewXY as overriddenWindowNewXY' {`Int',`Int', `Int', `Int', id `Ptr ()'} -> `Ptr ()' id #}
diff --git a/src/Graphics/UI/FLTK/LowLevel/Base/Group.chs b/src/Graphics/UI/FLTK/LowLevel/Base/Group.chs
--- a/src/Graphics/UI/FLTK/LowLevel/Base/Group.chs
+++ b/src/Graphics/UI/FLTK/LowLevel/Base/Group.chs
@@ -131,7 +131,7 @@
   runOp _ _ group = withRef group $ \groupPtr -> setResizable' groupPtr nullPtr
 
 {# fun Fl_Group_resizable as resizable' { id `Ptr ()' } -> `Ptr ()' id #}
-instance (impl ~ ( IO (Maybe (Ref Widget)))) => Op (GetResizable ()) GroupBase orig impl where
+instance (impl ~ ( IO (Maybe (Ref WidgetBase)))) => Op (GetResizable ()) GroupBase orig impl where
   runOp _ _ group = withRef group $ \groupPtr -> resizable' groupPtr >>= toMaybeRef
 
 {# fun Fl_Group_add_resizable as addResizable' { id `Ptr ()',id `Ptr ()' } -> `()' supressWarningAboutRes #}
@@ -230,7 +230,7 @@
 --
 -- getChild :: 'Ref' 'GroupBase' -> 'AtIndex' -> 'IO' ('Maybe' ('Ref' 'WidgetBase'))
 --
--- getResizable :: 'Ref' 'GroupBase' -> 'IO' ('Maybe' ('Ref' 'Widget'))
+-- getResizable :: 'Ref' 'GroupBase' -> 'IO' ('Maybe' ('Ref' 'WidgetBase'))
 --
 -- handle :: 'Ref' 'GroupBase' -> 'Event' -> 'IO' ('Either' 'UnknownEvent' ())
 --
diff --git a/src/Graphics/UI/FLTK/LowLevel/Base/Input.chs b/src/Graphics/UI/FLTK/LowLevel/Base/Input.chs
--- a/src/Graphics/UI/FLTK/LowLevel/Base/Input.chs
+++ b/src/Graphics/UI/FLTK/LowLevel/Base/Input.chs
@@ -15,9 +15,9 @@
      --
      -- $hierarchy
 
-     -- * Input
+     -- * Fl_Input functions
      --
-     -- $Input
+     -- $functions
     )
 where
 #include "Fl_ExportMacros.h"
diff --git a/src/Graphics/UI/FLTK/LowLevel/Base/MenuButton.chs b/src/Graphics/UI/FLTK/LowLevel/Base/MenuButton.chs
--- a/src/Graphics/UI/FLTK/LowLevel/Base/MenuButton.chs
+++ b/src/Graphics/UI/FLTK/LowLevel/Base/MenuButton.chs
@@ -81,7 +81,7 @@
     menuButtonDestroy' winPtr
     return nullPtr
 {#fun Fl_Menu_Button_popup as menuButtonPopup' { id `Ptr ()' } -> `Ptr ()' id #}
-instance (impl ~ ( IO (Maybe (Ref MenuItem)))) => Op (Popup ()) MenuButtonBase orig impl where
+instance (impl ~ ( IO (Maybe (Ref MenuItemBase)))) => Op (Popup ()) MenuButtonBase orig impl where
   runOp _ _ menu_bar = withRef menu_bar (\p -> menuButtonPopup' p >>= toMaybeRef)
 
 {# fun Fl_Menu_Button_draw_super as drawSuper' { id `Ptr ()' } -> `()' supressWarningAboutRes #}
@@ -142,7 +142,7 @@
 --
 -- hide :: 'Ref' 'MenuButtonBase' -> 'IO' ()
 --
--- popup :: 'Ref' 'MenuButtonBase' -> 'IO' ('Maybe' ('Ref' 'MenuItem'))
+-- popup :: 'Ref' 'MenuButtonBase' -> 'IO' ('Maybe' ('Ref' 'MenuItemBase'))
 --
 -- resize :: 'Ref' 'MenuButtonBase' -> 'Rectangle' -> 'IO' ()
 --
diff --git a/src/Graphics/UI/FLTK/LowLevel/Base/MenuItem.chs b/src/Graphics/UI/FLTK/LowLevel/Base/MenuItem.chs
--- a/src/Graphics/UI/FLTK/LowLevel/Base/MenuItem.chs
+++ b/src/Graphics/UI/FLTK/LowLevel/Base/MenuItem.chs
@@ -159,8 +159,8 @@
 instance (impl ~  IO (Bool)) => Op (Radio ()) MenuItemBase orig impl where
   runOp _ _ menu_item = withRef menu_item $ \menu_itemPtr -> radio' menu_itemPtr
 
-{# fun Fl_Menu_Item_value as value' { id `Ptr ()' } -> `Int' #}
-instance (impl ~  IO (Int)) => Op (GetValue ()) MenuItemBase orig impl where
+{# fun Fl_Menu_Item_value as value' { id `Ptr ()' } -> `Bool' cToBool #}
+instance (impl ~  IO (Bool)) => Op (GetValue ()) MenuItemBase orig impl where
   runOp _ _ menu_item = withRef menu_item $ \menu_itemPtr -> value' menu_itemPtr
 
 {# fun Fl_Menu_Item_set as set' { id `Ptr ()' } -> `()' #}
@@ -239,7 +239,7 @@
   runOp _ _ menu_item = withRef menu_item $ \menu_itemPtr -> text' menu_itemPtr >>= cStringToText
 
 {# fun Fl_Menu_Item_pulldown_with_args as pulldownWithArgs' { id `Ptr ()',`Int',`Int',`Int',`Int',id `Ptr ()', id `Ptr ()', id `Ptr ()', fromBool `Bool'} -> `Ptr ()' id #}
-instance (Parent a MenuPrimBase, Parent b MenuItemBase, Parent c MenuItemBase, impl ~ (Rectangle -> Maybe (Ref a) -> Maybe (Ref b) -> Maybe (Ref c) -> Maybe Bool -> IO (Maybe (Ref MenuItem)))) => Op (Pulldown ()) MenuItemBase orig impl where
+instance (Parent a MenuPrimBase, Parent b MenuItemBase, Parent c MenuItemBase, impl ~ (Rectangle -> Maybe (Ref a) -> Maybe (Ref b) -> Maybe (Ref c) -> Maybe Bool -> IO (Maybe (Ref MenuItemBase)))) => Op (Pulldown ()) MenuItemBase orig impl where
   runOp _ _ menu_item rectangle picked' template_menu title menu_barFlag =
     let (x_pos, y_pos, width, height) = fromRectangle rectangle
         menu_bar = maybe False id menu_barFlag
@@ -409,7 +409,7 @@
 --
 -- getText :: 'Ref' 'MenuItemBase' -> 'IO' 'T.Text'
 --
--- getValue :: 'Ref' 'MenuItemBase' -> 'IO' ('Int')
+-- getValue :: 'Ref' 'MenuItemBase' -> 'IO' ('Bool')
 --
 -- hide :: 'Ref' 'MenuItemBase' -> 'IO' ()
 --
@@ -423,7 +423,7 @@
 --
 -- popup:: ('Parent' a 'MenuItemBase', 'Parent' b 'MenuPrimBase', 'Parent' c 'MenuItemBase') => 'Ref' 'MenuItemBase' -> 'Position' -> 'Maybe' 'T.Text' -> 'Maybe' ('Ref' a) -> 'Maybe' ('Ref' b) -> 'IO' ('Maybe' ('Ref' c))
 --
--- pulldown:: ('Parent' a 'MenuPrimBase', 'Parent' b 'MenuItemBase', 'Parent' c 'MenuItemBase') => 'Ref' 'MenuItemBase' -> 'Rectangle' -> 'Maybe' ('Ref' a) -> 'Maybe' ('Ref' b) -> 'Maybe' ('Ref' c) -> 'Maybe' 'Bool' -> 'IO' ('Maybe' ('Ref' 'MenuItem'))
+-- pulldown:: ('Parent' a 'MenuPrimBase', 'Parent' b 'MenuItemBase', 'Parent' c 'MenuItemBase') => 'Ref' 'MenuItemBase' -> 'Rectangle' -> 'Maybe' ('Ref' a) -> 'Maybe' ('Ref' b) -> 'Maybe' ('Ref' c) -> 'Maybe' 'Bool' -> 'IO' ('Maybe' ('Ref' 'MenuItemBase'))
 --
 -- radio :: 'Ref' 'MenuItemBase' -> 'IO' ('Bool')
 --
diff --git a/src/Graphics/UI/FLTK/LowLevel/Base/Tabs.chs b/src/Graphics/UI/FLTK/LowLevel/Base/Tabs.chs
--- a/src/Graphics/UI/FLTK/LowLevel/Base/Tabs.chs
+++ b/src/Graphics/UI/FLTK/LowLevel/Base/Tabs.chs
@@ -142,7 +142,7 @@
 
 
 {# fun Fl_Tabs_value as value' { id `Ptr ()' } -> `Ptr ()' id #}
-instance (impl ~ (IO (Maybe (Ref Widget)))) => Op (GetValue ()) TabsBase orig impl where
+instance (impl ~ (IO (Maybe (Ref WidgetBase)))) => Op (GetValue ()) TabsBase orig impl where
    runOp _ _ tabs = withRef tabs $ \tabsPtr -> value' tabsPtr >>= toMaybeRef
 
 {# fun Fl_Tabs_set_value as setValue' { id `Ptr ()',id `Ptr ()' } -> `Int' #}
@@ -150,7 +150,7 @@
    runOp _ _ tabs w = withRef tabs $ \tabsPtr -> withMaybeRef w $ \wPtr -> setValue' tabsPtr wPtr >>= return . successOrNoChange
 
 {# fun Fl_Tabs_push as push' { id `Ptr ()' } -> `Ptr ()' id #}
-instance (impl ~ (IO (Maybe (Ref Widget)))) => Op (GetPush ()) TabsBase orig impl where
+instance (impl ~ (IO (Maybe (Ref WidgetBase)))) => Op (GetPush ()) TabsBase orig impl where
    runOp _ _ tabs = withRef tabs $ \tabsPtr -> push' tabsPtr >>= toMaybeRef
 
 {# fun Fl_Tabs_set_push as setPush' { id `Ptr ()',id `Ptr ()' } -> `Int' #}
@@ -158,7 +158,7 @@
    runOp _ _ tabs w = withRef tabs $ \tabsPtr -> withMaybeRef w $ \wPtr -> setPush' tabsPtr wPtr >>= return . successOrNoChange
 
 {# fun Fl_Tabs_which as which' { id `Ptr ()',`Int',`Int' } -> `Ptr ()' id #}
-instance (impl ~ (Position -> IO (Maybe (Ref Widget)))) => Op (Which ()) TabsBase orig impl where
+instance (impl ~ (Position -> IO (Maybe (Ref WidgetBase)))) => Op (Which ()) TabsBase orig impl where
    runOp _ _ tabs (Position (X event_x) (Y event_y)) = withRef tabs $ \tabsPtr -> which' tabsPtr event_x event_y >>= toMaybeRef
 
 {# fun Fl_Tabs_client_area_with_tabh as clientAreaWithTabh' { id `Ptr ()', alloca- `Int' peekIntConv*,alloca- `Int' peekIntConv*,alloca- `Int' peekIntConv*,alloca- `Int' peekIntConv*, `Int'} -> `()' #}
@@ -233,11 +233,11 @@
 --
 -- draw :: 'Ref' 'TabsBase' -> 'IO' ()
 --
--- getPush :: 'Ref' 'TabsBase' -> 'IO' ('Maybe' ('Ref' 'Widget'))
+-- getPush :: 'Ref' 'TabsBase' -> 'IO' ('Maybe' ('Ref' 'WidgetBase'))
 --
 -- getTabAlign :: 'Ref' 'TabsBase' -> 'IO' ('AlignType')
 --
--- getValue :: 'Ref' 'TabsBase' -> 'IO' ('Maybe' ('Ref' 'Widget'))
+-- getValue :: 'Ref' 'TabsBase' -> 'IO' ('Maybe' ('Ref' 'WidgetBase'))
 --
 -- handle :: 'Ref' 'TabsBase' -> 'Event' -> 'IO' ('Either' 'UnknownEvent' ())
 --
@@ -257,5 +257,5 @@
 --
 -- tabPositions :: 'Ref' 'TabsBase' -> 'IO' 'AtIndex'
 --
--- which :: 'Ref' 'TabsBase' -> 'Position' -> 'IO' ('Maybe' ('Ref' 'Widget'))
+-- which :: 'Ref' 'TabsBase' -> 'Position' -> 'IO' ('Maybe' ('Ref' 'WidgetBase'))
 -- @
diff --git a/src/Graphics/UI/FLTK/LowLevel/Base/Widget.chs b/src/Graphics/UI/FLTK/LowLevel/Base/Widget.chs
--- a/src/Graphics/UI/FLTK/LowLevel/Base/Widget.chs
+++ b/src/Graphics/UI/FLTK/LowLevel/Base/Widget.chs
@@ -424,8 +424,8 @@
 instance (impl ~ (IO ())) => Op (Deactivate ()) WidgetBase orig impl where
   runOp _ _ widget = withRef widget $ \widgetPtr -> deactivate' widgetPtr
 {# fun Fl_Widget_output as output' { id `Ptr ()' } -> `Int' #}
-instance (impl ~ (IO (Int))) => Op (GetOutput ()) WidgetBase orig impl where
-  runOp _ _ widget = withRef widget $ \widgetPtr -> output' widgetPtr
+instance (impl ~ (IO (Bool))) => Op (GetOutput ()) WidgetBase orig impl where
+  runOp _ _ widget = withRef widget $ \widgetPtr -> ((==) 0) <$> output' widgetPtr
 {# fun Fl_Widget_set_output as setOutput' { id `Ptr ()' } -> `()' supressWarningAboutRes #}
 instance (impl ~ (IO ())) => Op (SetOutput ()) WidgetBase orig impl where
   runOp _ _ widget = withRef widget $ \widgetPtr -> setOutput' widgetPtr
@@ -669,7 +669,7 @@
 --
 -- drawFocus :: 'Ref' 'WidgetBase' -> 'Maybe' ('Boxtype', 'Rectangle') -> 'IO' ()
 --
--- drawLabel :: 'Ref' 'WidgetBase' -> 'Maybe' ('Rectangle,Alignments') -> 'IO' ()
+-- drawLabel :: 'Ref' 'WidgetBase' -> 'Maybe' ('Rectangle', 'Alignments') -> 'IO' ()
 --
 -- flags :: 'Ref' 'WidgetBase' -> 'IO' ['WidgetFlag']
 --
@@ -681,7 +681,7 @@
 --
 -- getColor :: 'Ref' 'WidgetBase' -> 'IO' ('Color')
 --
--- getDamage :: 'Ref' 'WidgetBase' -> 'IO' (['Damage')]
+-- getDamage :: 'Ref' 'WidgetBase' -> 'IO' (['Damage'])
 --
 -- getDeimage :: 'Ref' 'WidgetBase' -> 'IO' ('Maybe' ('Ref' 'Image'))
 --
diff --git a/src/Graphics/UI/FLTK/LowLevel/Base/Window.chs b/src/Graphics/UI/FLTK/LowLevel/Base/Window.chs
--- a/src/Graphics/UI/FLTK/LowLevel/Base/Window.chs
+++ b/src/Graphics/UI/FLTK/LowLevel/Base/Window.chs
@@ -331,12 +331,12 @@
   runOp _ _ win = withRef win $ \winPtr -> iconize' winPtr
 
 {# fun Fl_Window_x_root as xRoot' { id `Ptr ()' } -> `Int' #}
-instance (impl ~ ( IO (Int))) => Op (GetXRoot ()) WindowBase orig impl where
-  runOp _ _ win = withRef win $ \winPtr -> xRoot' winPtr
+instance (impl ~ ( IO (X))) => Op (GetXRoot ()) WindowBase orig impl where
+  runOp _ _ win = withRef win $ \winPtr -> xRoot' winPtr >>= return . X
 
 {# fun Fl_Window_y_root as yRoot' { id `Ptr ()' } -> `Int' #}
-instance (impl ~ ( IO (Int))) => Op (GetYRoot ()) WindowBase orig impl where
-  runOp _ _ win = withRef win $ \winPtr -> yRoot' winPtr
+instance (impl ~ ( IO (Y))) => Op (GetYRoot ()) WindowBase orig impl where
+  runOp _ _ win = withRef win $ \winPtr -> yRoot' winPtr >>= return . Y
 
 {# fun Fl_Window_current as current' {  } -> `Ptr ()' id #}
 currentWindow ::  (Parent a WindowBase) => IO (Ref a)
@@ -515,11 +515,11 @@
 --
 -- getType_ :: 'Ref' 'WindowBase' -> 'IO' ('WindowType')
 --
--- getXRoot :: 'Ref' 'WindowBase' -> 'IO' ('Int')
+-- getXRoot :: 'Ref' 'WindowBase' -> 'IO' ('X')
 --
 -- getXclass :: 'Ref' 'WindowBase' -> 'IO' 'T.Text'
 --
--- getYRoot :: 'Ref' 'WindowBase' -> 'IO' ('Int')
+-- getYRoot :: 'Ref' 'WindowBase' -> 'IO' ('Y')
 --
 -- handle :: 'Ref' 'WindowBase' -> 'Event' -> 'IO' ('Either' 'UnknownEvent' ())
 --
diff --git a/src/Graphics/UI/FLTK/LowLevel/Box.chs b/src/Graphics/UI/FLTK/LowLevel/Box.chs
--- a/src/Graphics/UI/FLTK/LowLevel/Box.chs
+++ b/src/Graphics/UI/FLTK/LowLevel/Box.chs
@@ -95,6 +95,9 @@
 
 -- $hierarchy
 -- @
+-- "Graphics.UI.FLTK.LowLevel.Base.Widget"
+--  |
+--  v
 -- "Graphics.UI.FLTK.LowLevel.Widget"
 --  |
 --  v
diff --git a/src/Graphics/UI/FLTK/LowLevel/FLTKHS.hs b/src/Graphics/UI/FLTK/LowLevel/FLTKHS.hs
--- a/src/Graphics/UI/FLTK/LowLevel/FLTKHS.hs
+++ b/src/Graphics/UI/FLTK/LowLevel/FLTKHS.hs
@@ -1220,6 +1220,10 @@
 -- pointer to some initialized but empty chunk of memory and filling it up. The
 -- corresponding Haskell function just returns a 'Data.Text'.
 --
+-- (5) Widget destructors can be called explicitly with 'destroy'. The reason it
+-- is called 'destroy' instead of 'delete' to match C++ is that it is a mistake
+-- and it's too late to change it now.
+--
 --
 -- It is hoped that until the documentation becomes more self-sustaining the
 -- user can use these heuristics (and the type signatures) along with the
diff --git a/src/Graphics/UI/FLTK/LowLevel/Fl_Types.chs b/src/Graphics/UI/FLTK/LowLevel/Fl_Types.chs
--- a/src/Graphics/UI/FLTK/LowLevel/Fl_Types.chs
+++ b/src/Graphics/UI/FLTK/LowLevel/Fl_Types.chs
@@ -1,4 +1,4 @@
-{-# LANGUAGE CPP, EmptyDataDecls, ExistentialQuantification #-}
+{-# LANGUAGE CPP, EmptyDataDecls, ExistentialQuantification, RoleAnnotations #-}
 
 #ifdef CALLSTACK_AVAILABLE
 {-# LANGUAGE ImplicitParams #-}
@@ -265,6 +265,7 @@
 newtype NumRestyled = NumRestyled Int deriving (Show, Eq, Ord)
 newtype DeletedText = DeletedText T.Text deriving (Show, Eq, Ord)
 
+type role Ref nominal
 data Ref a           = Ref !(ForeignPtr (Ptr ())) deriving (Eq, Show, Ord)
 data FunRef          = FunRef !(FunPtr ())
 -- * The FLTK widget hierarchy
diff --git a/src/Graphics/UI/FLTK/LowLevel/Hierarchy.hs b/src/Graphics/UI/FLTK/LowLevel/Hierarchy.hs
--- a/src/Graphics/UI/FLTK/LowLevel/Hierarchy.hs
+++ b/src/Graphics/UI/FLTK/LowLevel/Hierarchy.hs
@@ -2144,7 +2144,7 @@
 type instance Functions DoubleWindowBase = DoubleWindowBaseFuncs
 
 data CDoubleWindow parent
-type DoubleWindow = CDoubleWindow WindowBase
+type DoubleWindow = CDoubleWindow DoubleWindowBase
 type DoubleWindowFuncs =
   (Destroy
   (Flush
@@ -2484,7 +2484,7 @@
 type instance Functions FillSliderBase = ()
 
 data CFillSlider parent
-type FillSlider = CFillSlider SliderBase
+type FillSlider = CFillSlider FillSliderBase
 
 type instance Functions FillSlider = ()
 
@@ -4733,7 +4733,7 @@
 type instance Functions ScrolledBase = ScrolledBaseFuncs
 
 data CScrolled parent
-type Scrolled = CScrolled Group
+type Scrolled = CScrolled ScrolledBase
 type ScrolledFuncs =
   (Resize
   (Draw
diff --git a/src/Graphics/UI/FLTK/LowLevel/Window.chs b/src/Graphics/UI/FLTK/LowLevel/Window.chs
--- a/src/Graphics/UI/FLTK/LowLevel/Window.chs
+++ b/src/Graphics/UI/FLTK/LowLevel/Window.chs
@@ -41,6 +41,7 @@
 
 {# fun Fl_Window_flush as flush' { id `Ptr ()' } -> `()' supressWarningAboutRes #}
 instance (impl ~ ( IO ())) => Op (Flush ()) Window orig impl where
+  runOp _ _ window = withRef window $ \windowPtr -> flush' windowPtr
 
 -- $hierarchy
 -- @
@@ -53,7 +54,7 @@
 -- "Graphics.UI.FLTK.LowLevel.Base.Window"
 --  |
 --  v
--- "Graphics.UI.FLTK.LowLevel.Window"runOp _ _ window = withRef window $ \windowPtr -> flush' windowPtr
+-- "Graphics.UI.FLTK.LowLevel.Window"
 -- @
 
 -- $functions