Add accessors for sealed member "flippable"

One step closer to makes GtkRange properly subclassable, but still
quite some accessors missing.

gtk/gtk.symbols

@@ -3294,6 +3294,7 @@ gtk_radio_tool_button_set_group
 #if IN_FILE(__GTK_RANGE_C__)
 gtk_range_get_adjustment
 gtk_range_get_fill_level
+gtk_range_get_flippable
 gtk_range_get_inverted
 gtk_range_get_lower_stepper_sensitivity
 gtk_range_get_restrict_to_fill_level
@@ -3304,6 +3305,7 @@ gtk_range_get_upper_stepper_sensitivity
 gtk_range_get_value
 gtk_range_set_adjustment
 gtk_range_set_fill_level
+gtk_range_set_flippable
 gtk_range_set_increments
 gtk_range_set_inverted
 gtk_range_set_lower_stepper_sensitivity

gtk/gtkrange.c

@@ -843,6 +843,52 @@ gtk_range_get_inverted (GtkRange *range)
   return range->inverted;
 }
 
+/**
+ * gtk_range_set_flippable:
+ * @range: a #GtkRange
+ * @flippable: %TRUE to make the range flippable
+ *
+ * If a range is flippable, it will switch its direction if it is
+ * horizontal and its direction is %GTK_TEXT_DIR_RTL.
+ *
+ * See gtk_widget_get_direction().
+ *
+ * Since: 2.18
+ **/
+void
+gtk_range_set_flippable (GtkRange *range,
+                         gboolean  flippable)
+{
+  g_return_if_fail (GTK_IS_RANGE (range));
+
+  flippable = flippable ? TRUE : FALSE;
+
+  if (flippable != range->flippable)
+    {
+      range->flippable = flippable;
+
+      gtk_widget_queue_draw (GTK_WIDGET (range));
+    }
+}
+
+/**
+ * gtk_range_get_flippable:
+ * @range: a #GtkRange
+ *
+ * Gets the value set by gtk_range_set_flippable().
+ *
+ * Return value: %TRUE if the range is flippable
+ *
+ * Since: 2.18
+ **/
+gboolean
+gtk_range_get_flippable (GtkRange *range)
+{
+  g_return_val_if_fail (GTK_IS_RANGE (range), FALSE);
+
+  return range->flippable;
+}
+
 /**
  * gtk_range_set_lower_stepper_sensitivity:
  * @range:       a #GtkRange

gtk/gtkrange.h

@@ -147,6 +147,10 @@ void               gtk_range_set_inverted                  (GtkRange      *range
                                                             gboolean       setting);
 gboolean           gtk_range_get_inverted                  (GtkRange      *range);
 
+void               gtk_range_set_flippable                 (GtkRange      *range,
+                                                            gboolean       flippable);
+gboolean           gtk_range_get_flippable                 (GtkRange      *range);
+
 void               gtk_range_set_lower_stepper_sensitivity (GtkRange      *range,
                                                             GtkSensitivityType sensitivity);
 GtkSensitivityType gtk_range_get_lower_stepper_sensitivity (GtkRange      *range);