===================================================================
RCS file: /cvsrepo/anoncvs/cvs/src/usr.bin/tmux/tty-features.c,v
retrieving revision 1.2
retrieving revision 1.3
diff -c -r1.2 -r1.3
*** src/usr.bin/tmux/tty-features.c	2020/04/20 13:38:48	1.2
--- src/usr.bin/tmux/tty-features.c	2020/04/20 15:37:32	1.3
***************
*** 1,4 ****
! /* $OpenBSD: tty-features.c,v 1.2 2020/04/20 13:38:48 nicm Exp $ */
  
  /*
   * Copyright (c) 2020 Nicholas Marriott <nicholas.marriott@gmail.com>
--- 1,4 ----
! /* $OpenBSD: tty-features.c,v 1.3 2020/04/20 15:37:32 nicm Exp $ */
  
  /*
   * Copyright (c) 2020 Nicholas Marriott <nicholas.marriott@gmail.com>
***************
*** 232,238 ****
  	return (s);
  }
  
! void
  tty_apply_features(struct tty_term *term, int feat)
  {
  	const struct tty_feature	 *tf;
--- 232,238 ----
  	return (s);
  }
  
! int
  tty_apply_features(struct tty_term *term, int feat)
  {
  	const struct tty_feature	 *tf;
***************
*** 240,246 ****
  	u_int				  i;
  
  	if (feat == 0)
! 		return;
  	log_debug("applying terminal features: %s", tty_get_features(feat));
  
  	for (i = 0; i < nitems(tty_features); i++) {
--- 240,246 ----
  	u_int				  i;
  
  	if (feat == 0)
! 		return (0);
  	log_debug("applying terminal features: %s", tty_get_features(feat));
  
  	for (i = 0; i < nitems(tty_features); i++) {
***************
*** 259,263 ****
--- 259,266 ----
  		}
  		term->flags |= tf->flags;
  	}
+ 	if ((term->features | feat) == term->features)
+ 		return (0);
  	term->features |= feat;
+ 	return (1);
  }