diff --git a/CHANGES b/CHANGES
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,7 @@
+0.4.4 - 110413
+* got rid of impredicative types (using unsafeCoerce...)
+* cleaned up warnings
+
 0.4.3 - 100315
 * fixed a compilation error
 
diff --git a/hp2any-manager.cabal b/hp2any-manager.cabal
--- a/hp2any-manager.cabal
+++ b/hp2any-manager.cabal
@@ -1,5 +1,5 @@
 Name:          hp2any-manager
-Version:       0.4.3
+Version:       0.4.4
 Cabal-Version: >= 1.2
 Synopsis:      A utility to visualise and compare heap profiles.
 Category:      profiling, development, utils
@@ -9,8 +9,8 @@
   time in the style of a tiling window manager.
 
 Author:        Patai Gergely
-Maintainer:    Patai Gergely (patai@iit.bme.hu)
-Copyright:     (c) 2009, Patai Gergely
+Maintainer:    Patai Gergely (patai.gergely@gmail.com)
+Copyright:     (c) 2009-2011, Patai Gergely
 Homepage:      http://www.haskell.org/haskellwiki/Hp2any
 License:       BSD3
 License-File:  LICENSE
@@ -24,7 +24,6 @@
   README
 
 Executable hp2any-manager
-  Executable:     hp2any-manager
   HS-Source-Dirs: src
   Main-IS:        Manager.hs
   Build-Depends:  base >= 4 && < 5, containers, array, filepath, time,
diff --git a/src/Manager.hs b/src/Manager.hs
--- a/src/Manager.hs
+++ b/src/Manager.hs
@@ -1,5 +1,5 @@
-{-# LANGUAGE ExistentialQuantification, ImpredicativeTypes #-}
-{-# OPTIONS_GHC -Wall -fno-warn-missing-signatures -fno-warn-name-shadowing #-}
+{-# LANGUAGE ExistentialQuantification, NoMonomorphismRestriction #-}
+{-# OPTIONS_GHC -Wall -fno-warn-missing-signatures -fno-warn-name-shadowing -fno-warn-unused-do-bind #-}
 
 import Control.Applicative
 import Control.Concurrent
@@ -14,7 +14,7 @@
 import Data.Time.Clock
 --import Graphics.Rendering.Cairo as C
 import Graphics.Rendering.OpenGL as GL hiding (get,samples)
-import Graphics.Rendering.OpenGL.GL.DisplayLists
+--import Graphics.Rendering.OpenGL.GL.DisplayLists
 import Graphics.UI.Gtk as Gtk
 import Graphics.UI.Gtk.Gdk.Events
 import Graphics.UI.Gtk.Glade
@@ -24,9 +24,10 @@
 import Profiling.Heap.Types
 import Profiling.Heap.Stats
 import System.FilePath
-import System.Glib.Types
+--import System.Glib.Types
 import System.IO.Unsafe
 import Text.Printf
+import Unsafe.Coerce
 
 import Paths_hp2any_manager (getDataFileName)
 
@@ -52,13 +53,12 @@
 {-| Load the subtree of the UI description belonging to the widget of
 the given name and return the function to extract widgets from it. -}
 
-loadWidget :: String -> IO (forall w . WidgetClass w => (GObject -> w) -> String -> IO w)
+loadWidget :: String -> IO ((GObject -> Widget) -> String -> IO Widget)
 loadWidget name = do
   fileName <- getDataFileName "src/manager.glade"
   xml <- fromMaybe (error ("Error loading widget " ++ name)) <$>
          xmlNewWithRootAndDomain fileName (Just name) Nothing
-  return ((\cast name -> xmlGetWidget xml cast name) ::
-          forall w . WidgetClass w => (GObject -> w) -> String -> IO w)
+  return (\cast name -> xmlGetWidget xml cast name)
 
 {-| Insert the widget before the last child of the given box.  If
 there's no last child, the insertion still happens. -}
@@ -155,7 +155,9 @@
 
 makeProgressWindow :: IO (Window, String -> IO (), SetProgress, IO () -> IO ())
 makeProgressWindow = do
-  getWidget <- loadWidget "progressWindow"
+  getWidget_ <- loadWidget "progressWindow"
+  let getWidget :: WidgetClass w => (GObject -> w) -> String -> IO w
+      getWidget = unsafeCoerce getWidget_
 
   progressWindow <- getWidget castToWindow "progressWindow"
   cancelButton <- getWidget castToButton "cancelProgressButton"
@@ -475,8 +477,12 @@
 
 makeProfileGraph :: Profile -> IO VBox
 makeProfileGraph prof = do
-  getWidget <- loadWidget "graphWidget"
-  getMenuWidget <- loadWidget "graphMenu"
+  getWidget_ <- loadWidget "graphWidget"
+  getMenuWidget_ <- loadWidget "graphMenu"
+  let getWidget :: WidgetClass w => (GObject -> w) -> String -> IO w
+      getWidget = unsafeCoerce getWidget_
+      getMenuWidget :: WidgetClass w => (GObject -> w) -> String -> IO w
+      getMenuWidget = unsafeCoerce getMenuWidget_
 
   graphWidget <- getWidget castToVBox "graphWidget"