From 1dbbf91b4b3f24e81534dbd5c537bc9b161d07e5 Mon Sep 17 00:00:00 2001
From: Spencer Janssen <spencerjanssen@gmail.com>
Date: Tue, 7 Oct 2008 23:20:53 +0200
Subject: Partial fix for #40

Improvements:
 - clicking on the root will change focus to that screen
 - moving the mouse from a window on a screen to an empty screen changes focus
   to that screen
The only remaining issue is that moving the mouse between two empty screens
does not change focus.  In order to solve this, we'd have to select motion events
on the root window, which is potentially expensive.

darcs-hash:20081007212053-25a6b-ccec914ace595db38dc035a3b56478bdbf1cc6d3
---
 XMonad/Operations.hs | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/XMonad/Operations.hs b/XMonad/Operations.hs
index 40a1a38..5f7d39a 100644
--- a/XMonad/Operations.hs
+++ b/XMonad/Operations.hs
@@ -294,11 +294,17 @@ setTopFocus = withWindowSet $ maybe (setFocusX =<< asks theRoot) setFocusX . W.p
 -- This happens if X notices we've moved the mouse (and perhaps moved
 -- the mouse to a new screen).
 focus :: Window -> X ()
-focus w = withWindowSet $ \s -> do
-    if W.member w s then when (W.peek s /= Just w) $ do
-                              local (\c -> c { mouseFocused = True }) $ do
-                                  windows (W.focusWindow w)
-                    else whenX (isRoot w) $ setFocusX w
+focus w = local (\c -> c { mouseFocused = True }) $ withWindowSet $ \s -> do
+    let stag = W.tag . W.workspace
+        curr = stag $ W.current s
+    mnew <- maybe (return Nothing) (fmap (fmap stag) . uncurry pointScreen)
+            =<< asks mousePosition
+    root <- asks theRoot
+    case () of
+        _ | W.member w s && W.peek s /= Just w -> windows (W.focusWindow w)
+          | Just new <- mnew, w == root && curr /= new
+                                               -> windows (W.view new)
+          | otherwise                          -> return ()
 
 -- | Call X to set the keyboard focus details.
 setFocusX :: Window -> X ()
@@ -311,7 +317,7 @@ setFocusX w = withWindowSet $ \ws -> do
             setButtonGrab True otherw
 
     -- If we ungrab buttons on the root window, we lose our mouse bindings.
-    whenX (not <$> isRoot w) $ setButtonGrab False w
+    whenX (isRoot w) $ setButtonGrab False w
     io $ do setInputFocus dpy w revertToPointerRoot 0
             -- raiseWindow dpy w
 
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