diff --git a/ChangeLog.md b/ChangeLog.md
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -1,5 +1,11 @@
 # Revision history for wild-bind-indicator
 
+## 0.2.0.0  -- 2018-01-01
+
+* Modify constraints of `withNumPadIndicator`, `wildBindWithIndicator`, `bindingHook` functions.
+* Add `adaptIndicator`, `toggleBinding` functions.
+
+
 ## 0.1.0.1  -- 2016-09-22
 
 * First version. Released on an unsuspecting world.
diff --git a/src/WildBind/Indicator.hs b/src/WildBind/Indicator.hs
--- a/src/WildBind/Indicator.hs
+++ b/src/WildBind/Indicator.hs
@@ -1,3 +1,4 @@
+{-# LANGUAGE OverloadedStrings #-}
 -- |
 -- Module: WildBind.Indicator
 -- Description: Graphical indicator for WildBind
@@ -21,6 +22,10 @@
          setPresence,
          togglePresence,
          quit,
+         -- ** Conversion
+         adaptIndicator,
+         -- ** Binding
+         toggleBinding,
          -- * Generalization of number pad types
          NumPadPosition(..)
        ) where
@@ -56,7 +61,8 @@
 import System.IO (stderr, hPutStrLn)
 
 import WildBind ( ActionDescription, Option(optBindingHook),
-                  FrontEnd(frontDefaultDescription), Binding,
+                  FrontEnd(frontDefaultDescription), Binding, Binding',
+                  binding, Action(Action),
                   wildBind', defOption
                 )
 import WildBind.Input.NumPad (NumPadUnlocked(..), NumPadLocked(..))
@@ -79,9 +85,13 @@
     setPresence :: Bool -> IO (),
     -- ^ Set the presence of the indicator.
 
-    quit :: IO ()
+    quit :: IO (),
     -- ^ Destroy the indicator. This usually means quitting the entire
     -- application.
+
+    allButtons :: [i]
+    -- ^ list of all buttons on which the indicator displays
+    -- descriptions.
   }
 
 -- | Toggle the presence of the indicator.
@@ -91,11 +101,11 @@
 -- | Convert actions in the input 'Indicator' so that those actions
 -- can be executed from a non-GTK-main thread.
 transportIndicator :: Indicator s i -> Indicator s i
-transportIndicator ind = Indicator { updateDescription = \i d -> postGUIAsync $ updateDescription ind i d,
-                                     getPresence = postGUISync $ getPresence ind,
-                                     setPresence = \visible -> postGUIAsync $ setPresence ind visible,
-                                     quit = postGUISync $ quit ind
-                                   }
+transportIndicator ind = ind { updateDescription = \i d -> postGUIAsync $ updateDescription ind i d,
+                               getPresence = postGUISync $ getPresence ind,
+                               setPresence = \visible -> postGUIAsync $ setPresence ind visible,
+                               quit = postGUISync $ quit ind
+                             }
 
 
 -- | Something that can be mapped to number pad's key positions.
@@ -153,7 +163,7 @@
 -- 
 -- The executable must be compiled by ghc with __@-threaded@ option enabled.__
 -- Otherwise, it aborts.
-withNumPadIndicator :: NumPadPosition i => (Indicator s i -> IO ()) -> IO ()
+withNumPadIndicator :: (NumPadPosition i, Enum i, Bounded i) => (Indicator s i -> IO ()) -> IO ()
 withNumPadIndicator action = if rtsSupportsBoundThreads then impl else error_impl where
   error_impl = throwIO $ userError "You need to build with -threaded option when you use WildBind.Indicator.withNumPadIndicator function."
   impl = do
@@ -172,7 +182,8 @@
           { updateDescription = \i d -> updater i d,
             getPresence = G.get win widgetVisible,
             setPresence = \visible -> if visible then widgetShowAll win else widgetHide win,
-            quit = mainQuit
+            quit = mainQuit,
+            allButtons = enumFromTo minBound maxBound
           }
     liftIO $ void $ G.on win deleteEvent $ do
       liftIO $ widgetHide win
@@ -194,13 +205,13 @@
 
 -- | Run 'WildBind.wildBind' with the given 'Indicator'. 'ActionDescription's
 -- are shown by the 'Indicator'.
-wildBindWithIndicator :: (Ord i, Enum i, Bounded i) => Indicator s i -> Binding s i -> FrontEnd s i -> IO ()
-wildBindWithIndicator ind binding front = wildBind' (defOption { optBindingHook = bindingHook ind front }) binding front
+wildBindWithIndicator :: Ord i => Indicator s i -> Binding s i -> FrontEnd s i -> IO ()
+wildBindWithIndicator ind b front = wildBind' (defOption { optBindingHook = bindingHook ind front }) b front
 
 -- | Create an action appropriate for 'optBindingHook' in 'Option'
 -- from 'Indicator' and 'FrontEnd'.
-bindingHook :: (Ord i, Enum i, Bounded i) => Indicator s1 i -> FrontEnd s2 i -> [(i, ActionDescription)] -> IO ()
-bindingHook ind front bind_list = forM_ (enumFromTo minBound maxBound) $ \input -> do
+bindingHook :: Ord i => Indicator s1 i -> FrontEnd s2 i -> [(i, ActionDescription)] -> IO ()
+bindingHook ind front bind_list = forM_ (allButtons ind) $ \input -> do
   let desc = M.findWithDefault (frontDefaultDescription front input) input (M.fromList bind_list)
   updateDescription ind input desc
                        
@@ -291,3 +302,34 @@
     checkMenuItemSetActive toggler =<< getPresence ind
     void $ G.on toggler checkMenuItemToggled (togglePresence ind)
     return toggler
+
+-- | Map input type of 'Indicator', so that it can adapt to the new
+-- input type @i'@.
+--
+-- If the contra-mapper function returns 'Nothing', those input
+-- symbols are ignored by the 'Indicator'.
+--
+-- @since 0.2.0.0
+adaptIndicator :: (i -> i') -- ^ mapper function
+               -> (i' -> Maybe i) -- ^ contra-mapper function
+               -> Indicator s i -- ^ original
+               -> Indicator s i' -- ^ adapted indicator
+adaptIndicator mapper cmapper ind =
+  ind { updateDescription = newDesc,
+        allButtons = map mapper $ allButtons ind
+      }
+  where
+    newDesc input = case cmapper input of
+      Nothing -> const $ return ()
+      Just orig_input -> updateDescription ind orig_input
+
+-- | A binding that toggles presence of the 'Indicator'.
+--
+-- @since 0.2.0.0
+toggleBinding :: (NumPadPosition i, Ord i, Enum i, Bounded i)
+              => Indicator s i
+              -> NumPadLocked -- ^ the button to bind the 'togglePresence' action
+              -> Binding' bs fs i
+toggleBinding ind button = binding $ map (\input -> (input, Action "Toggle description" $ togglePresence ind)) help_likes
+  where
+    help_likes = filter ((== button) . toNumPad) $ enumFromTo minBound maxBound
diff --git a/wild-bind-indicator.cabal b/wild-bind-indicator.cabal
--- a/wild-bind-indicator.cabal
+++ b/wild-bind-indicator.cabal
@@ -1,5 +1,5 @@
 name:                   wild-bind-indicator
-version:                0.1.0.1
+version:                0.2.0.0
 author:                 Toshio Ito <debug.ito@gmail.com>
 maintainer:             Toshio Ito <debug.ito@gmail.com>
 license:                BSD3
@@ -19,7 +19,7 @@
   default-language:     Haskell2010
   hs-source-dirs:       src
   ghc-options:          -Wall -fno-warn-unused-imports
-  default-extensions:   OverloadedStrings
+  other-extensions:     OverloadedStrings
   exposed-modules:      WildBind.Indicator
   other-modules:        Paths_wild_bind_indicator
   build-depends:        base >=4.6 && <5.0,