updated for version 7.3.214
Problem:    The text displayed by ":z-" isn't exactly like old Vi.
Solution:   Add one to the start line number. (ChangZhuo Chen)
diff --git a/src/ex_cmds.c b/src/ex_cmds.c
index 64c1371..43e861a 100644
--- a/src/ex_cmds.c
+++ b/src/ex_cmds.c
@@ -4097,8 +4097,8 @@
     switch (*kind)
     {
 	case '-':
-	    start = lnum - bigness * (linenr_T)(x - kind);
-	    end = start + bigness;
+	    start = lnum - bigness * (linenr_T)(x - kind) + 1;
+	    end = start + bigness - 1;
 	    curs = end;
 	    break;