display cleanup only targets the right-most field where it's needed

doc/fixes36.2

@@ -169,6 +169,7 @@ tty: ensure that current status fields are always copied to prior status
 	values so that comparisons are correct
 tty: fix an out of bounds error in tty_status_update() for BL_HUNGER case
 tty: fix leftover display artifact when last field on the row got smaller
+	and optimize so only the right-most field requires the cleanup code
 X11: its use of genl_status_update exposed a negative index use that could
 	lead to a segfault
 

include/wintty.h

@@ -229,6 +229,8 @@ E short FDECL(set_tty_font_name, (winid, char *));
 #endif
 E char *NDECL(tty_get_color_string);
 #endif
+E void FDECL(tty_status_enablefield,
+             (int, const char *, const char *, BOOLEAN_P));
 E void NDECL(tty_status_init);
 E void FDECL(tty_status_update, (int, genericptr_t, int, int, int, unsigned long *));
 

win/tty/wintty.c

@@ -103,7 +103,7 @@ struct window_procs tty_procs = {
 #endif
     tty_getmsghistory, tty_putmsghistory,
     tty_status_init,
-    genl_status_finish, genl_status_enablefield,
+    genl_status_finish, tty_status_enablefield,
 #ifdef STATUS_HILITES
     tty_status_update,
 #else
@@ -3599,6 +3599,18 @@ tty_status_init()
     genl_status_init();
 }
 
+void
+tty_status_enablefield(fieldidx, nm, fmt, enable)
+int fieldidx;
+const char *nm;
+const char *fmt;
+boolean enable;
+{
+    genl_status_enablefield(fieldidx, nm, fmt, enable);
+    /* force re-evaluation of last field on the row */
+    setlast = FALSE;
+}
+
 void
 do_setlast()
 {
@@ -3606,7 +3618,7 @@ do_setlast()
 
     setlast = TRUE;
     for (row = 0; row < 2; ++row)
-        for (i = MAX_PER_ROW - 1; i ; --i) {
+        for (i = MAX_PER_ROW - 1; i > 0; --i) {
            fld = fieldorder[row][i];
 
            if (fld == BL_FLUSH || !status_activefields[fld])