diff --git a/src/Graphics/X11/Turtle.hs b/src/Graphics/X11/Turtle.hs
--- a/src/Graphics/X11/Turtle.hs
+++ b/src/Graphics/X11/Turtle.hs
@@ -23,6 +23,7 @@
 	xcor,
 	ycor,
 	heading,
+	towards,
 	distance,
 
 	pendown,
@@ -47,6 +48,8 @@
 
 	windowWidth,
 	windowHeight,
+	onclick,
+	waitField,
 
 	xturtleVersion
 ) where
@@ -55,7 +58,7 @@
 	Field, Layer, Character,
 	forkIOX, openField, closeField,
 	addCharacter, addLayer, layerSize, clearLayer, clearCharacter,
-	addThread, fieldColor,
+	addThread, fieldColor, onclick, waitField,
 	moveTurtle
  )
 import Graphics.X11.TurtleInput(
@@ -70,9 +73,10 @@
 import Data.IORef(IORef, newIORef, readIORef, modifyIORef)
 import Data.Bits(shift, (.|.))
 import Data.Word(Word8)
+import Data.Fixed(mod')
 
 xturtleVersion :: (Int, String)
-xturtleVersion = (16, "0.0.9")
+xturtleVersion = (18, "0.0.11")
 
 data Turtle = Turtle {
 	layer :: Layer,
@@ -204,7 +208,17 @@
 ycor = fmap snd . position
 
 heading :: Turtle -> IO Double
-heading t = fmap (direction . (states t !!)) $ readIORef $ stateIndex t
+heading t = do
+	deg <- getDegrees t
+	dir <- fmap (direction . (states t !!)) $ readIORef $ stateIndex t
+	return $ dir `mod'` deg
+
+towards :: Turtle -> Double -> Double -> IO Double
+towards t x0 y0 = do
+	(x, y) <- position t
+	deg <- getDegrees t
+	let	dir = atan2 (y0 - y) (x0 - x) * deg / (2 * pi)
+	return $ if dir < 0 then dir + deg else dir
 
 distance :: Turtle -> Double -> Double -> IO Double
 distance t x0 y0 = do
diff --git a/src/Graphics/X11/TurtleMove.hs b/src/Graphics/X11/TurtleMove.hs
--- a/src/Graphics/X11/TurtleMove.hs
+++ b/src/Graphics/X11/TurtleMove.hs
@@ -13,6 +13,8 @@
 	clearCharacter,
 	addThread,
 	fieldColor,
+	onclick,
+	waitField,
 
 	moveTurtle
 ) where
@@ -25,7 +27,7 @@
 	drawLine, drawCharacter, drawCharacterAndLine, undoLayer,
 	drawLineNotFlush,
 	clearCharacter, addThread,
-	fieldColor
+	fieldColor, onclick, waitField
  )
 
 import Control.Concurrent(threadDelay)
diff --git a/src/Graphics/X11/WindowLayers.hs b/src/Graphics/X11/WindowLayers.hs
--- a/src/Graphics/X11/WindowLayers.hs
+++ b/src/Graphics/X11/WindowLayers.hs
@@ -5,6 +5,7 @@
 
 	openField,
 	closeField,
+	waitField,
 	fieldColor,
 	layerSize,
 
@@ -21,6 +22,8 @@
 	clearLayer,
 	flushLayer,
 
+	onclick,
+
 	forkIOX,
 	addThread
 ) where
@@ -38,7 +41,7 @@
 	fillRectangle, fillPolygon, nonconvex, coordModeOrigin,
 
 	setWMProtocols, selectInput, allocaXEvent, nextEvent,
-	keyPressMask, exposureMask,
+	keyPressMask, exposureMask, buttonPressMask,
 
 	getGeometry, initThreads, connectionNumber, pending, destroyWindow
  )
@@ -59,6 +62,7 @@
 	killThread, threadDelay)
 
 import System.Posix.Types
+import Foreign.C.Types
 
 data Field = Field{
 	fDisplay :: Display,
@@ -78,7 +82,9 @@
 	fEvent :: Chan (Maybe Event),
 	fClose :: Chan (),
 	fClosed :: IORef Bool,
-	fRunning :: IORef [ThreadId]
+	fRunning :: IORef [ThreadId],
+	fOnclick :: IORef (Double -> Double -> IO Bool),
+	fEnd :: Chan ()
  }
 
 data Layer = Layer{
@@ -108,7 +114,7 @@
 	setForeground dpy gcBG 0xffffff
 	forM_ bufs $ \bf -> fillRectangle dpy bf gcBG 0 0 rWidth rHeight
 	setWMProtocols dpy win [del]
-	selectInput dpy win $ exposureMask .|. keyPressMask
+	selectInput dpy win $ exposureMask .|. keyPressMask .|. buttonPressMask
 	mapWindow dpy win
 	[widthRef, heightRef] <- mapM newIORef [rWidth, rHeight]
 	buffActions <- newIORef []
@@ -119,6 +125,8 @@
 	close <- newChan
 	closed <- newIORef False
 	running <- newIORef []
+	onclickRef <- newIORef $ const $ const $ return True
+	endRef <- newChan
 	writeChan wait ()
 	let f = Field{
 		fDisplay = dpy,
@@ -138,7 +146,9 @@
 		fEvent = event,
 		fClose = close,
 		fClosed = closed,
-		fRunning = running
+		fRunning = running,
+		fOnclick = onclickRef,
+		fEnd = endRef
 	 }
 	_ <- forkIOX $ runLoop f
 	flushWindow f
@@ -155,7 +165,7 @@
 			writeChan (fEvent f) $ Just ev
 		end <- readChan endc
 		when end $ writeChan (fEvent f) Nothing
-	(>> closeDisplay (fDisplay f)) $
+	(>> (closeDisplay (fDisplay f) >> writeChan (fEnd f) ())) $
 		(>> destroyWindow (fDisplay f) (fWindow f)) $ doWhile_ $ do
 		mev <- readChan $ fEvent f
 		case mev of
@@ -167,11 +177,17 @@
 				redrawAll f
 				return True
 			Just (KeyEvent{}) -> return True
-			Just ev@(ClientMessageEvent{}) ->
+			Just ev@ButtonEvent{} -> do
+				pos <- convertPosRev f (ev_x ev) (ev_y ev)
+				readIORef (fOnclick f) >>= ($ pos) . uncurry
+			Just ev@ClientMessageEvent{} ->
 				return $ convert (head $ ev_data ev) /= fDel f
 			Nothing -> killThread th1 >> return False
 			_ -> return True
 
+onclick :: Field -> (Double -> Double -> IO Bool) -> IO ()
+onclick f act = writeIORef (fOnclick f) act
+
 fieldColor :: Field -> Pixel -> IO ()
 fieldColor f clr = do
 	setForeground (fDisplay f) (fGCBG f) clr
@@ -324,6 +340,11 @@
 	return $ (round . (+ width / 2) *** round . (+ height / 2) . negate)
 		`map` ps
 
+convertPosRev :: Field -> CInt -> CInt -> IO (Double, Double)
+convertPosRev f x y = do
+	(width, height) <- fieldSize f
+	return $ (fromIntegral x - width / 2, fromIntegral (- y) + height / 2)
+
 fieldSize :: Field -> IO (Double, Double)
 fieldSize w = fmap (fromIntegral *** fromIntegral) $ winSize w
 
@@ -371,3 +392,6 @@
 	ret <- act f
 	writeChan (fWait f) ()
 	return ret
+
+waitField :: Field -> IO ()
+waitField = readChan . fEnd
diff --git a/xturtle.cabal b/xturtle.cabal
--- a/xturtle.cabal
+++ b/xturtle.cabal
@@ -2,7 +2,7 @@
 cabal-version:	>= 1.6
 
 name:		xturtle
-version:	0.0.10
+version:	0.0.11
 stability:	experimental
 author:		Yoshikuni Jujo <PAF01143@nifty.ne.jp>
 maintainer:	Yoshikuni Jujo <PAF01143@nifty.ne.jp>