diff --git a/LambdaINet.cabal b/LambdaINet.cabal
--- a/LambdaINet.cabal
+++ b/LambdaINet.cabal
@@ -1,5 +1,5 @@
 name:          LambdaINet
-version:       0.1.1
+version:       0.1.2
 homepage:      not available
 maintainer:    Paul H. Liu <paul@thev.net>
 cabal-version: >= 1.6
@@ -19,8 +19,11 @@
 data-files:    font.tga
 
 executable LambdaINet
-  Main-is:        Main.lhs
+  Main-is:  Main.lhs
   Other-Modules:  Diagram INet Lambda
+  if os(darwin)
+    Other-Modules:  EnableGUI
+    cpp-options:    -D_EnableGUI_
   Build-Depends:  base >= 3 && < 5, OpenGL, GLFW, containers, mtl
   Hs-Source-Dirs: src
 
diff --git a/README b/README
--- a/README
+++ b/README
@@ -12,6 +12,9 @@
 CHANGES
 =======
 
+*   Tue Sep 15 EDT 2009 - fix GUI on OS X; fix glitch when moving nodes. 
+                          bump version to 0.1.2.
+
 *   Mon Sep 14 EDT 2009 - fix the bug with app function, bump version to 0.1.1.
 
 USAGE
diff --git a/src/Diagram.lhs b/src/Diagram.lhs
--- a/src/Diagram.lhs
+++ b/src/Diagram.lhs
@@ -448,11 +448,8 @@
 >       let ax' = ax + truncate (realToFrac (mx' - mx) / scale / unit)
 >           ay' = ay + truncate (realToFrac (my - my') / scale / unit)
 >           i = atomID atom
->           moved = abs (ax' - ax) >= 1 || abs (ay' - ay) >= 1
->           posMap' = if moved
->                       then adjust (\ ((x, y), d) -> ((ax', ay'), d)) i posMap 
->                       else posMap
->           r'@(_, render) = if moved then renderDiagram posMap' d else r
+>           posMap' = adjust (\ ((x, y), d) -> ((ax', ay'), d)) i posMap 
+>           r'@(_, render) = renderDiagram posMap' d
 >       if status == GLFW.Release
 >         then return (UserAction $ buttonReleased d r', render)
 >         else return (UserAction $ buttonHolding but d r' atom s, render)
diff --git a/src/EnableGUI.hs b/src/EnableGUI.hs
new file mode 100644
--- /dev/null
+++ b/src/EnableGUI.hs
@@ -0,0 +1,21 @@
+{-# LANGUAGE ForeignFunctionInterface #-}
+
+module EnableGUI(enableGUI) where
+
+import Data.Int
+import Foreign
+
+type ProcessSerialNumber = Int64
+
+foreign import ccall "GetCurrentProcess" getCurrentProcess :: Ptr ProcessSerialNumber -> IO Int16
+foreign import ccall "_CGSDefaultConnection" cgsDefaultConnection :: IO ()
+foreign import ccall "CPSEnableForegroundOperation" cpsEnableForegroundOperation :: Ptr ProcessSerialNumber -> IO ()
+foreign import ccall "CPSSignalAppReady" cpsSignalAppReady :: Ptr ProcessSerialNumber -> IO ()
+foreign import ccall "CPSSetFrontProcess" cpsSetFrontProcess :: Ptr ProcessSerialNumber -> IO ()
+
+enableGUI = alloca $ \psn -> do
+    getCurrentProcess psn
+    cgsDefaultConnection
+    cpsEnableForegroundOperation psn
+    cpsSignalAppReady psn
+    cpsSetFrontProcess psn
diff --git a/src/Main.lhs b/src/Main.lhs
--- a/src/Main.lhs
+++ b/src/Main.lhs
@@ -1,6 +1,6 @@
 The main program for Lambdascope
 
-> {-# LANGUAGE RecursiveDo #-}
+> {-# LANGUAGE RecursiveDo,CPP #-}
 
 > module Main where
 
@@ -24,7 +24,12 @@
 
 Main Program
 
+#ifdef _EnableGUI_
+> import EnableGUI
+> main = enableGUI >> do
+#else
 > main = do
+#endif
 >   GLFW.initialize
 >   initWindow w h
 >   showHelp <- newIORef False