diff --git a/src/include/lib3270.h b/src/include/lib3270.h
index c8184f9..0f245b0 100644
--- a/src/include/lib3270.h
+++ b/src/include/lib3270.h
@@ -454,13 +454,26 @@
 	/**
 	 * @brief Register a function interested in a state change.
 	 *
-	 * @param h		Session handle.
-	 * @param tx	State ID
-	 * @param func	Callback
-	 * @param data	Data
+	 * @param hSession	Session handle.
+	 * @param tx		State ID
+	 * @param func		Callback
+	 * @param data		Data
+	 *
+	 * @return State change identifier.
+	 *
+	 */
+	LIB3270_EXPORT const void * lib3270_register_schange(H3270 *hSession, LIB3270_STATE tx, void (*func)(H3270 *, int, void *),void *data);
+
+	/**
+	 * @brief Unregister a function interested in a state change.
+	 *
+	 * @param hSession	Session handle.
+	 * @param id		State change identifier.
+	 *
+	 * @return 0 if suceeds, non zero if fails (sets errno).
 	 *
 	 */
-	LIB3270_EXPORT void lib3270_register_schange(H3270 *h,LIB3270_STATE tx, void (*func)(H3270 *, int, void *),void *data);
+	LIB3270_EXPORT int lib3270_unregister_schange(H3270 *hSession, LIB3270_STATE tx, void * id);
 
 	LIB3270_EXPORT void lib3270_reset_callbacks(H3270 *hSession);
 
diff --git a/src/lib3270/host.c b/src/lib3270/host.c
index 53d5f5b..c834051 100644
--- a/src/lib3270/host.c
+++ b/src/lib3270/host.c
@@ -167,26 +167,66 @@ void lib3270_set_disconnected(H3270 *hSession)
 
 /**
  * @brief Register a function interested in a state change.
+ *
+ * @param hSession	Session handle.
+ * @param tx		State ID
+ * @param func		Callback
+ * @param data		Data
+ *
+ * @return State change identifier.
+ *
  */
-LIB3270_EXPORT void lib3270_register_schange(H3270 *h, LIB3270_STATE tx, void (*func)(H3270 *, int, void *),void *data)
+LIB3270_EXPORT const void * lib3270_register_schange(H3270 *hSession, LIB3270_STATE tx, void (*func)(H3270 *, int, void *),void *data)
 {
 	struct lib3270_state_callback *st;
 
-    CHECK_SESSION_HANDLE(h);
+    CHECK_SESSION_HANDLE(hSession);
 
 	st 			= (struct lib3270_state_callback *) lib3270_malloc(sizeof(struct lib3270_state_callback));
 	st->func	= func;
 	st->data	= data;
 
-	if (h->st_last[tx])
-		h->st_last[tx]->next = st;
+	if (hSession->st.last[tx])
+		hSession->st.last[tx]->next = st;
 	else
-		h->st_callbacks[tx] = st;
+		hSession->st.callbacks[tx] = st;
+
+	hSession->st.last[tx] = st;
 
-	h->st_last[tx] = st;
+	return (void *) st;
 
 }
 
+LIB3270_EXPORT int lib3270_unregister_schange(H3270 *hSession, LIB3270_STATE tx, void * id)
+{
+	struct lib3270_state_callback *st;
+	struct lib3270_state_callback *prev = (struct lib3270_state_callback *) NULL;
+
+	for (st = hSession->st.callbacks[tx]; st != (struct lib3270_state_callback *) NULL; st = (struct lib3270_state_callback *) st->next)
+	{
+		if (st == (struct lib3270_state_callback *)id)
+			break;
+
+		prev = st;
+	}
+
+	if (st == (struct lib3270_state_callback *)NULL)
+	{
+		lib3270_write_log(hSession,"lib3270","Invalid call to (%s): %p wasnt found in the list",__FUNCTION__,id);
+		return errno = ENOENT;
+	}
+
+	if (prev != (struct lib3270_state_callback *) NULL)
+		prev->next = st->next;
+	else
+		hSession->st.callbacks[tx] = (struct lib3270_state_callback *) st->next;
+
+	lib3270_free(id);
+
+	return 0;
+}
+
+
 /**
  * @brief Signal a state change.
  */
@@ -214,7 +254,7 @@ void lib3270_st_changed(H3270 *h, LIB3270_STATE tx, int mode)
 
 	trace("%s is %d on session %p",state_name[tx],mode,h);
 
-	for (st = h->st_callbacks[tx];st;st = st->next)
+	for(st = h->st.callbacks[tx];st;st = st->next)
 	{
 		st->func(h,mode,st->data);
 	}
@@ -449,23 +489,23 @@ LIB3270_EXPORT const char * lib3270_get_luname(H3270 *h)
 LIB3270_EXPORT int lib3270_has_active_script(H3270 *h)
 {
     CHECK_SESSION_HANDLE(h);
-	return (h->oia_flag[LIB3270_FLAG_SCRIPT] != 0);
+	return (h->oia.flag[LIB3270_FLAG_SCRIPT] != 0);
 }
 
 LIB3270_EXPORT int lib3270_get_typeahead(H3270 *h)
 {
     CHECK_SESSION_HANDLE(h);
-	return (h->oia_flag[LIB3270_FLAG_TYPEAHEAD] != 0);
+	return (h->oia.flag[LIB3270_FLAG_TYPEAHEAD] != 0);
 }
 
 LIB3270_EXPORT int lib3270_get_undera(H3270 *h)
 {
     CHECK_SESSION_HANDLE(h);
-	return (h->oia_flag[LIB3270_FLAG_UNDERA] != 0);
+	return (h->oia.flag[LIB3270_FLAG_UNDERA] != 0);
 }
 
 LIB3270_EXPORT int lib3270_get_oia_box_solid(H3270 *h)
 {
     CHECK_SESSION_HANDLE(h);
-	return (h->oia_flag[LIB3270_FLAG_BOXSOLID] != 0);
+	return (h->oia.flag[LIB3270_FLAG_BOXSOLID] != 0);
 }
diff --git a/src/lib3270/private.h b/src/lib3270/private.h
index 72ecca3..25267e2 100644
--- a/src/lib3270/private.h
+++ b/src/lib3270/private.h
@@ -366,14 +366,16 @@ struct _h3270
 		char	   	    	* qualified;
 	} host;
 
-	char					* proxy;			/**< Proxy server (type:host[:port]) */
+	// char					* proxy;			/**< Proxy server (type:host[:port]) */
 	char					* termname;
 
 	struct lib3270_charset	  charset;
 
-	LIB3270_MESSAGE			  oia_status;
-
-	unsigned char	 		  oia_flag[LIB3270_FLAG_COUNT];
+	struct
+	{
+		LIB3270_MESSAGE		  status;
+		unsigned char		  flag[LIB3270_FLAG_COUNT];
+	} oia;
 
 	unsigned short			  current_port;
 
@@ -630,9 +632,11 @@ struct _h3270
 		void *userdata;
 	} trace;
 
-	// Callbacks.
-	struct lib3270_state_callback		* st_callbacks[LIB3270_STATE_USER];
-	struct lib3270_state_callback		* st_last[LIB3270_STATE_USER];
+	// State change listeners.
+	struct {
+		struct lib3270_state_callback	* callbacks[LIB3270_STATE_USER];
+		struct lib3270_state_callback	* last[LIB3270_STATE_USER];
+	} st;
 
 };
 
diff --git a/src/lib3270/properties.c b/src/lib3270/properties.c
index d51b06a..24c45e9 100644
--- a/src/lib3270/properties.c
+++ b/src/lib3270/properties.c
@@ -641,9 +641,9 @@ LIB3270_EXPORT int lib3270_get_secure_host(H3270 *hSession)
 
 }
 
+#ifdef SSL_ENABLE_CRL_CHECK
 LIB3270_EXPORT char * lib3270_get_ssl_crl_text(H3270 *hSession)
 {
-#ifdef SSL_ENABLE_CRL_CHECK
 
 	if(hSession->ssl.crl.cert)
 	{
@@ -666,11 +666,16 @@ LIB3270_EXPORT char * lib3270_get_ssl_crl_text(H3270 *hSession)
 
 	}
 
+	return NULL;
 
-#endif // SSL_ENABLE_CRL_CHECK
-
+}
+#else
+LIB3270_EXPORT char * lib3270_get_ssl_crl_text(H3270 *hSession unused)
+{
 	return NULL;
 }
+#endif // SSL_ENABLE_CRL_CHECK
+
 
 LIB3270_EXPORT char * lib3270_get_ssl_peer_certificate_text(H3270 *hSession)
 {
diff --git a/src/lib3270/screen.c b/src/lib3270/screen.c
index 049e4e8..af21e99 100644
--- a/src/lib3270/screen.c
+++ b/src/lib3270/screen.c
@@ -545,8 +545,8 @@ void set_status(H3270 *session, LIB3270_FLAG id, Boolean on)
 {
 	CHECK_SESSION_HANDLE(session);
 
-	session->oia_flag[id] = (on != 0);
-	session->cbk.update_oia(session,id,session->oia_flag[id]);
+	session->oia.flag[id] = (on != 0);
+	session->cbk.update_oia(session,id,session->oia.flag[id]);
 
 }
 
@@ -640,7 +640,7 @@ void status_reset(H3270 *session)
 LIB3270_EXPORT LIB3270_MESSAGE lib3270_get_program_message(H3270 *session)
 {
 	CHECK_SESSION_HANDLE(session);
-	return session->oia_status;
+	return session->oia.status;
 }
 
 /**
@@ -655,8 +655,8 @@ LIB3270_EXPORT LIB3270_MESSAGE lib3270_lock_status(H3270 *hSession)
 {
 	CHECK_SESSION_HANDLE(hSession);
 
-	if(hSession->oia_status)
-		return hSession->oia_status;
+	if(hSession->oia.status)
+		return hSession->oia.status;
 
 	if(hSession->kybdlock)
 		return LIB3270_MESSAGE_KYBDLOCK;
@@ -683,10 +683,10 @@ void status_changed(H3270 *session, LIB3270_MESSAGE id)
 {
 	CHECK_SESSION_HANDLE(session);
 
-	if(id == session->oia_status || id < 0)
+	if(id == session->oia.status || id < 0)
 		return;
 
-	session->oia_status = id;
+	session->oia.status = id;
 
 	session->cbk.update_status(session,id);
 }
diff --git a/src/lib3270/session.c b/src/lib3270/session.c
index 0e22cb5..212c676 100644
--- a/src/lib3270/session.c
+++ b/src/lib3270/session.c
@@ -91,11 +91,11 @@ void lib3270_session_free(H3270 *h)
 	// Release state change callbacks
 	for(f=0;f<LIB3270_STATE_USER;f++)
 	{
-		while(h->st_callbacks[f])
+		while(h->st.callbacks[f])
 		{
-			struct lib3270_state_callback *next = h->st_callbacks[f]->next;
-			lib3270_free(h->st_callbacks[f]);
-			h->st_callbacks[f] = next;
+			struct lib3270_state_callback *next = h->st.callbacks[f]->next;
+			lib3270_free(h->st.callbacks[f]);
+			h->st.callbacks[f] = next;
 		}
 	}
 
@@ -321,7 +321,7 @@ static void lib3270_session_init(H3270 *hSession, const char *model, const char 
 	hSession->sock					= -1;
 	hSession->model_num				= -1;
 	hSession->cstate				= LIB3270_NOT_CONNECTED;
-	hSession->oia_status			= -1;
+	hSession->oia.status			= -1;
 	hSession->kybdlock 				= KL_NOT_CONNECTED;
 	hSession->aid 					= AID_NO;
 	hSession->reply_mode 			= SF_SRM_FIELD;
--
libgit2 0.21.2