X.H.EwmhDesktops: Fix _NET_ACTIVE_WINDOW requests from pagers being ignored

This makes window switching apps like rofi and alttab able to activate
windows even if the logHook doesn't activate them (which it doesn't by
default, and that's a regression).

Related: xmonad#396
Related: xmonad#110

Author: liskin

XMonad/Hooks/EwmhDesktops.hs

@@ -272,9 +272,14 @@ handle f (ClientMessageEvent {ev_window = w, ev_message_type = mt, ev_data = d})
                           | otherwise -> trace $ "Bad _NET_DESKTOP with data[0]="++show n
                     _ -> trace $ "Bad _NET_DESKTOP with data="++show d
             | mt == a_aw -> do
-                lh <- asks (logHook . config)
-                XS.put (NetActivated (Just w))
-                lh
+                case d of
+                    -- when the request comes from a pager, honor it unconditionally
+                    -- https://specifications.freedesktop.org/wm-spec/wm-spec-1.3.html#sourceindication
+                    (2:_) -> windows $ W.focusWindow w
+                    _ -> do
+                        lh <- asks (logHook . config)
+                        XS.put (NetActivated (Just w))
+                        lh
             | mt == a_cw ->
                 killWindow w
             | otherwise ->