* A given key will be written at most once while saving a session.
* Keys may be up to 255 characters long. String values have no length
* limit.
+ *
+ * Any returned error message must be freed after use.
*/
-void *open_settings_w(const char *sessionname);
+void *open_settings_w(const char *sessionname, char **errmsg);
void write_setting_s(void *handle, const char *key, const char *value);
void write_setting_i(void *handle, const char *key, int value);
void write_setting_filename(void *handle, const char *key, Filename value);