+ /**
+ * Returns the offset to show the drag handle.
+ */
+ virtual int scale_handle_offset() const = 0;
+
+ /**
+ * Handles the scale handle being dragged to an offset.
+ * @param offset the offset the scale handle was dragged to.
+ */
+ virtual void scale_handle_dragged(int offset) = 0;
+
+ /**
+ * Handles the scale handle being being released.
+ */
+ virtual void scale_handle_released() {};
+