widgets: Add GimpDeviceManager signal to reconfigure pad devices

In order to apply the pad configuration so it does something, we
need to create GtkPadController objects on each toplevel for each
configured pad device.

This signal will work as a hint that a new GtkPadController should
be generated for the given device and current configuration. At
the moment, emit it when pad devices are added or removed.

app/widgets/gimpdevicemanager.c

@@ -46,6 +46,12 @@ enum
   PROP_CURRENT_DEVICE
 };
 
+enum
+{
+  CONFIGURE_PAD,
+  LAST_SIGNAL
+};
+
 
 
 struct _GimpDeviceManagerPrivate
@@ -104,6 +110,8 @@ static void   gimp_device_manager_device_defaults (GdkSeat           *seat,
 G_DEFINE_TYPE_WITH_PRIVATE (GimpDeviceManager, gimp_device_manager,
                             GIMP_TYPE_LIST)
 
+static guint device_manager_signals[LAST_SIGNAL];
+
 #define parent_class gimp_device_manager_parent_class
 
 
@@ -118,6 +126,14 @@ gimp_device_manager_class_init (GimpDeviceManagerClass *klass)
   object_class->set_property       = gimp_device_manager_set_property;
   object_class->get_property       = gimp_device_manager_get_property;
 
+  device_manager_signals[CONFIGURE_PAD] =
+    g_signal_new ("configure-pad",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST, 0,
+                  NULL, NULL, NULL,
+                  G_TYPE_NONE, 1,
+                  GIMP_TYPE_DEVICE_INFO);
+
   g_object_class_install_property (object_class, PROP_GIMP,
                                    g_param_spec_object ("gimp",
                                                         NULL, NULL,
@@ -511,6 +527,9 @@ gimp_device_manager_device_added (GdkSeat           *seat,
       gimp_container_add (GIMP_CONTAINER (manager), GIMP_OBJECT (device_info));
       g_object_unref (device_info);
     }
+
+  if (gdk_device_get_source (device) == GDK_SOURCE_TABLET_PAD)
+    g_signal_emit (manager, device_manager_signals[CONFIGURE_PAD], 0, device_info);
 }
 
 static void
@@ -536,6 +555,9 @@ gimp_device_manager_device_removed (GdkSeat           *seat,
 
           gimp_device_manager_set_current_device (manager, device_info);
         }
+
+      if (gdk_device_get_source (device) == GDK_SOURCE_TABLET_PAD)
+        g_signal_emit (manager, device_manager_signals[CONFIGURE_PAD], 0, device_info);
     }
 }