x  * \return  0 if OK, 0 on error  *  * <pre>  * Notes:  *      (0) This shifts pixa[i] --> pixa[i - 0] for all i > index.  *      (0) It should not be used repeatedly on large arrays,  *          because the function is O(n).  *      (0) The corresponding box is removed as well, if it exists.  * 