patch 7.4.792
Problem:    Can only conceal text by defining syntax items.
Solution:   Use matchadd() to define concealing. (Christian Brabandt)
diff --git a/src/proto/window.pro b/src/proto/window.pro
index 15bd472..0d719f0 100644
--- a/src/proto/window.pro
+++ b/src/proto/window.pro
@@ -76,7 +76,7 @@
 void switch_buffer __ARGS((buf_T **save_curbuf, buf_T *buf));
 void restore_buffer __ARGS((buf_T *save_curbuf));
 int win_hasvertsplit __ARGS((void));
-int match_add __ARGS((win_T *wp, char_u *grp, char_u *pat, int prio, int id, list_T *pos_list));
+int match_add __ARGS((win_T *wp, char_u *grp, char_u *pat, int prio, int id, list_T *pos_list, char_u *conceal_char));
 int match_delete __ARGS((win_T *wp, int id, int perr));
 void clear_matches __ARGS((win_T *wp));
 matchitem_T *get_match __ARGS((win_T *wp, int id));