window: set the corresponding client pointer on focused windows.

The client window determines the device pair that is used for
core protocol calls such as XQueryPointer(), so different
clients using the core protocol can be focused by different
devices simultaneously.

src/core/window-private.h

@@ -660,6 +660,10 @@ void meta_window_propagate_focus_appearance (MetaWindow *window,
                                              MetaDevice *keyboard,
                                              gboolean    focused);
 
+void         meta_window_set_client_pointer (MetaWindow *window,
+                                             MetaDevice *pointer);
+MetaDevice * meta_window_get_client_pointer (MetaWindow *window);
+
 MetaDevice * meta_window_guess_grab_pointer (MetaWindow *window);
 
 #endif

src/core/window.c

@@ -6754,6 +6754,8 @@ meta_window_notify_focus (MetaWindow *window,
               !meta_prefs_get_raise_on_click())
             meta_display_ungrab_focus_window_button (window->display, window);
 
+          meta_window_set_client_pointer (window,
+                                          meta_device_get_paired_device (keyboard));
           g_signal_emit (window, window_signals[FOCUS], 0);
 
           if (meta_device_get_id (keyboard) == META_CORE_KEYBOARD_ID)
@@ -10523,6 +10525,32 @@ meta_window_get_frame_bounds (MetaWindow *window)
   return window->frame_bounds;
 }
 
+void
+meta_window_set_client_pointer (MetaWindow *window,
+                                MetaDevice *pointer)
+{
+#ifdef HAVE_XINPUT2
+  XISetClientPointer (window->display->xdisplay,
+                      window->xwindow,
+                      meta_device_get_id (pointer));
+#endif
+}
+
+MetaDevice *
+meta_window_get_client_pointer (MetaWindow *window)
+{
+  int device_id = META_CORE_POINTER_ID;
+
+#ifdef HAVE_XINPUT2
+  if (window->display->have_xinput2)
+    XIGetClientPointer (window->display->xdisplay,
+                        window->xwindow, &device_id);
+#endif
+
+  return meta_device_map_lookup (window->display->device_map,
+                                 device_id);
+}
+
 /* Guesses the better device to grab on if a grab is to be started,
  * only should be be used in circumstances where we don't know a
  * device at all.