X.A.GridSelect: Add gs_cancelOnEmptyClick field

In the original code, when a GridSelect is shown, user has to use
keyboard to cancel it (ESC key by default). With this field added,
when it is set to True (the default), mouse click on empty space
can cancel the GridSelect.

CHANGES.md

@@ -20,6 +20,14 @@
       myFunc` should be changed to `historyCompletionP myConf myFunc`.
       If not `myConf` is lying around, `def` can be used instead.
 
+  * `XMonad.Actions.GridSelect`
+
+    - Added the `gs_cancelOnEmptyClick` field to `GSConfig`, which makes
+      mouse clicks into "empty space" cancel the current grid-select.
+      Users explicitly defining their own `GSConfig` record will have to
+      add this to their definitions. Additionally, the field defaults to
+      `True`—to retain the old behaviour, set it to `False`.
+
 ### New Modules
 
   * `XMonad.Actions.Profiles`

XMonad/Actions/GridSelect.hs

@@ -203,10 +203,13 @@ data GSConfig a = GSConfig {
       gs_colorizer :: a -> Bool -> X (String, String),
       gs_font :: String,
       gs_navigate :: TwoD a (Maybe a),
+      -- ^ Customize key bindings for a GridSelect
       gs_rearranger :: Rearranger a,
       gs_originFractX :: Double,
       gs_originFractY :: Double,
-      gs_bordercolor :: String
+      gs_bordercolor :: String,
+      gs_cancelOnEmptyClick :: Bool
+      -- ^ When True, click on empty space will cancel GridSelect
 }
 
 -- | That is 'fromClassName' if you are selecting a 'Window', or
@@ -386,13 +389,20 @@ updateElementsWithColorizer colorizer elementmap = do
 stdHandle :: Event -> TwoD a (Maybe a) -> TwoD a (Maybe a)
 stdHandle ButtonEvent{ ev_event_type = t, ev_x = x, ev_y = y } contEventloop
     | t == buttonRelease = do
-        s@TwoDState { td_paneX = px, td_paneY = py,
-                         td_gsconfig = (GSConfig ch cw _ _ _ _ _ _ _ _) } <- get
+        s@TwoDState{ td_paneX = px
+                   , td_paneY = py
+                   , td_gsconfig = GSConfig{ gs_cellheight = ch
+                                           , gs_cellwidth = cw
+                                           , gs_cancelOnEmptyClick = cancelOnEmptyClick
+                                           }
+                   } <- get
         let gridX = (fi x - (px - cw) `div` 2) `div` cw
             gridY = (fi y - (py - ch) `div` 2) `div` ch
         case lookup (gridX,gridY) (td_elementmap s) of
              Just (_,el) -> return (Just el)
-             Nothing -> contEventloop
+             Nothing     -> if cancelOnEmptyClick
+                           then return Nothing
+                           else contEventloop
     | otherwise = contEventloop
 
 stdHandle ExposeEvent{} contEventloop = updateAllElements >> contEventloop
@@ -648,7 +658,7 @@ gridselect gsconfig elements =
     liftIO $ mapWindow dpy win
     liftIO $ selectInput dpy win (exposureMask .|. keyPressMask .|. buttonReleaseMask)
     status <- io $ grabKeyboard dpy win True grabModeAsync grabModeAsync currentTime
-    io $ grabPointer dpy win True buttonReleaseMask grabModeAsync grabModeAsync none none currentTime
+    void $ io $ grabPointer dpy win True buttonReleaseMask grabModeAsync grabModeAsync none none currentTime
     font <- initXMF (gs_font gsconfig)
     let screenWidth = toInteger $ rect_width scr
         screenHeight = toInteger $ rect_height scr
@@ -706,7 +716,7 @@ decorateName' w = do
 
 -- | Builds a default gs config from a colorizer function.
 buildDefaultGSConfig :: (a -> Bool -> X (String,String)) -> GSConfig a
-buildDefaultGSConfig col = GSConfig 50 130 10 col "xft:Sans-8" defaultNavigation noRearranger (1/2) (1/2) "white"
+buildDefaultGSConfig col = GSConfig 50 130 10 col "xft:Sans-8" defaultNavigation noRearranger (1/2) (1/2) "white" True
 
 -- | Brings selected window to the current workspace.
 bringSelected :: GSConfig Window -> X ()