+/**
+Message handler object
+used for
+<ul>
+<li>Error messages
+<li>Warning messages
+<li>Debugging messages
+</ul>
+*/
+//typedef struct opj_event_mgr
+//{
+// /** Data to call the event manager upon */
+// void * m_error_data;
+// /** Data to call the event manager upon */
+// void * m_warning_data;
+// /** Data to call the event manager upon */
+// void * m_info_data;
+// /** Error message callback if available, NULL otherwise */
+// opj_msg_callback error_handler;
+// /** Warning message callback if available, NULL otherwise */
+// opj_msg_callback warning_handler;
+// /** Debug message callback if available, NULL otherwise */
+// opj_msg_callback info_handler;
+//} opj_event_mgr_t;