notebook_wheel_scroll.patch

Index: gtk/gtknotebook.c
===================================================================
--- a/gtk/gtknotebook.c
+++ b/gtk/gtknotebook.c
@@ -383,6 +383,8 @@ static gboolean gtk_notebook_draw
                                               cairo_t          *cr);
 static gboolean gtk_notebook_button_press    (GtkWidget        *widget,
                                               GdkEventButton   *event);
+static gboolean gtk_notebook_scroll          (GtkWidget        *widget,
+                                              GdkEventScroll   *event);
 static gboolean gtk_notebook_button_release  (GtkWidget        *widget,
                                               GdkEventButton   *event);
 static gboolean gtk_notebook_popup_menu      (GtkWidget        *widget);
@@ -741,6 +743,7 @@ gtk_notebook_class_init (GtkNotebookClas
   widget_class->drag_failed = gtk_notebook_drag_failed;
   widget_class->compute_expand = gtk_notebook_compute_expand;
   widget_class->direction_changed = gtk_notebook_direction_changed;
+  widget_class->scroll_event = gtk_notebook_scroll;
 
   container_class->add = gtk_notebook_add;
   container_class->remove = gtk_notebook_remove;
@@ -1985,7 +1988,8 @@ gtk_notebook_realize (GtkWidget *widget)
   attributes.event_mask = gtk_widget_get_events (widget);
   attributes.event_mask |= (GDK_BUTTON_PRESS_MASK |
                             GDK_BUTTON_RELEASE_MASK | GDK_KEY_PRESS_MASK |
-                            GDK_POINTER_MOTION_MASK | GDK_ENTER_NOTIFY_MASK | GDK_LEAVE_NOTIFY_MASK);
+                            GDK_POINTER_MOTION_MASK | GDK_ENTER_NOTIFY_MASK |
+                            GDK_LEAVE_NOTIFY_MASK | GDK_SCROLL_MASK);
   attributes_mask = GDK_WA_X | GDK_WA_Y;
 
   priv->event_window = gdk_window_new (gtk_widget_get_parent_window (widget),
@@ -2340,6 +2344,52 @@ gtk_notebook_get_preferred_tabs_size (Gt
     }
 }
 
+static gboolean
+gtk_notebook_scroll (GtkWidget      *widget,
+                     GdkEventScroll *event)
+{
+  GtkNotebook *notebook = GTK_NOTEBOOK (widget);
+  GtkNotebookPrivate *priv = notebook->priv;
+  GtkWidget *child, *event_widget;
+  gint i;
+
+  if (!priv->cur_page)
+    return FALSE;
+
+  if (g_getenv ("GTK_NO_TAB_SCROLL") != FALSE)
+    return FALSE;
+
+  child = priv->cur_page->child;
+  event_widget = gtk_get_event_widget ((GdkEvent *)event);
+
+  /* ignore scroll events from the content of the page */
+  if (!event_widget || gtk_widget_is_ancestor (event_widget, child) || event_widget == child)
+    return FALSE;
+
+  /* nor from the action area */
+  for (i = 0; i < 2; i++)
+    {
+      if (event_widget == priv->action_widget[i] ||
+          (priv->action_widget[i] &&
+           gtk_widget_is_ancestor (event_widget, priv->action_widget[i])))
+        return FALSE;
+    }
+
+  switch (event->direction)
+    {
+    case GDK_SCROLL_RIGHT:
+    case GDK_SCROLL_DOWN:
+      gtk_notebook_next_page (notebook);
+      break;
+    case GDK_SCROLL_LEFT:
+    case GDK_SCROLL_UP:
+      gtk_notebook_prev_page (notebook);
+      break;
+    }
+
+  return TRUE;
+}
+
 static void
 gtk_notebook_measure_tabs (GtkCssGadget   *gadget,
                            GtkOrientation  orientation,