path: root/mail/mutt-devel/files/extra-patch-edit-threads

diff -ru work.old/mutt-1.5.6/OPS work/mutt-1.5.6/OPS
--- OPS	Wed Nov  5 10:41:31 2003
+++ OPS	Tue Feb 10 14:40:41 2004
@@ -96,6 +96,7 @@
 OP_LIST_REPLY "reply to specified mailing list"
 OP_MACRO "execute a macro"
 OP_MAIL "compose a new mail message"
+OP_MAIN_BREAK_THREAD "break the thread in two"
 OP_MAIN_CHANGE_FOLDER "open a different folder"
 OP_MAIN_CHANGE_FOLDER_READONLY "open a different folder in read only mode"
 OP_MAIN_CLEAR_FLAG "clear a status flag from a message"
@@ -105,6 +106,7 @@
 OP_MAIN_FIRST_MESSAGE "move to the first message"
 OP_MAIN_LAST_MESSAGE "move to the last message"
 OP_MAIN_LIMIT "show only messages matching a pattern"
+OP_MAIN_LINK_THREADS "link tagged message to the current one"
 OP_MAIN_NEXT_NEW "jump to the next new message"
 OP_MAIN_NEXT_NEW_THEN_UNREAD "jump to the next new or unread message"
 OP_MAIN_NEXT_SUBTHREAD "jump to the next subthread"
diff -ru work.old/mutt-1.5.6/acconfig.h work/mutt-1.5.6/acconfig.h
--- acconfig.h	Tue Jan 21 11:50:49 2003
+++ acconfig.h	Tue Feb 10 14:40:41 2004
@@ -36,3 +36,7 @@
  * all return values other than (size_t)(-1) as equivalent. */
 #undef ICONV_NONTRANS
 
+/* Do you want to use the rethreading functions with IMAP
+ * (--enable-imap-edit-threads) */
+#undef IMAP_EDIT_THREADS
+
diff -ru work.old/mutt-1.5.6/config.h.in work/mutt-1.5.6/config.h.in
--- config.h.in	Sun Feb  1 18:18:21 2004
+++ config.h.in	Tue Feb 10 14:40:41 2004
@@ -549,3 +549,7 @@
  * all return values other than (size_t)(-1) as equivalent. */
 #undef ICONV_NONTRANS
 
+/* Do you want to use the rethreading functions with IMAP
+ * (--enable-imap-edit-threads) */
+#undef IMAP_EDIT_THREADS
+
diff -ru work.old/mutt-1.5.6/configure work/mutt-1.5.6/configure
--- configure	Sun Feb  1 19:22:06 2004
+++ configure	Tue Feb 10 14:40:41 2004
@@ -40,6 +40,8 @@
 ac_help="$ac_help
     --with-gss[=PFX]         Compile in GSSAPI authentication for IMAP"
 ac_help="$ac_help
+  --enable-imap-edit-threads Enable editing threads support for IMAP"
+ac_help="$ac_help
   --with-ssl[=PFX]           Compile in SSL support for POP/IMAP"
 ac_help="$ac_help
   --with-nss[=PFX]           Compile in SSL support for POP/IMAP via NSS"
@@ -5383,6 +5385,23 @@
 else
   USE_GSS_TRUE='#'
   USE_GSS_FALSE=
+fi
+
+
+# Check whether --enable-imap-edit-threads or --disable-imap-edit-threads was given.
+if test "${enable_imap_edit_threads+set}" = set; then
+  enableval="$enable_imap_edit_threads"
+  
+  if test "$enableval" = "yes"; then
+    if test "$need_imap" = "yes"; then
+      cat >> confdefs.h <<\EOF
+#define IMAP_EDIT_THREADS 1
+EOF
+
+    else
+      echo "configure: warning: IMAP support for edit_threads is only useful with IMAP support" 1>&2
+    fi
+fi
 fi
 
 
diff -ru work.old/mutt-1.5.6/configure.in work/mutt-1.5.6/configure.in
--- configure.in	Sun Feb  1 19:22:05 2004
+++ configure.in	Tue Feb 10 14:40:41 2004
@@ -559,6 +559,16 @@
 
 dnl -- end imap dependencies --
 
+AC_ARG_ENABLE(imap-edit-threads, [  --enable-imap-edit-threads Enable editing threads support for IMAP],
+[
+  if test "$enableval" = "yes"; then
+    if test "$need_imap" = "yes"; then
+      AC_DEFINE(IMAP_EDIT_THREADS)
+    else
+      AC_MSG_WARN([IMAP support for edit_threads is only useful with IMAP support])
+    fi
+fi])
+
 AC_ARG_WITH(ssl, [  --with-ssl[=PFX]           Compile in SSL support for POP/IMAP],
 [       if test "$with_ssl" != "no"
         then
diff -ru work.old/mutt-1.5.6/copy.c work/mutt-1.5.6/copy.c
--- copy.c	Wed Nov  5 10:41:31 2003
+++ copy.c	Tue Feb 10 14:40:41 2004
@@ -95,6 +95,12 @@
 	    (ascii_strncasecmp ("Content-Length:", buf, 15) == 0 ||
 	     ascii_strncasecmp ("Lines:", buf, 6) == 0))
 	  continue;
+	if ((flags & CH_UPDATE_REFS) &&
+	    ascii_strncasecmp ("References:", buf, 11) == 0)
+	  continue;
+	if ((flags & CH_UPDATE_IRT) &&
+	    ascii_strncasecmp ("In-Reply-To:", buf, 12) == 0)
+	  continue;
 	ignore = 0;
       }
 
@@ -193,6 +199,12 @@
 	     ascii_strncasecmp ("type:", buf + 8, 5) == 0)) ||
 	   ascii_strncasecmp ("mime-version:", buf, 13) == 0))
 	continue;
+      if ((flags & CH_UPDATE_REFS) &&
+	  ascii_strncasecmp ("References:", buf, 11) == 0)
+	continue;
+      if ((flags & CH_UPDATE_IRT) &&
+	  ascii_strncasecmp ("In-Reply-To:", buf, 12) == 0)
+	continue;
 
       /* Find x -- the array entry where this header is to be saved */
       if (flags & CH_REORDER)
@@ -326,6 +338,8 @@
  	CH_XMIT		ignore Lines: and Content-Length:
  	CH_WEED		do header weeding
 	CH_NOQFROM      ignore ">From " line
+	CH_UPDATE_IRT	update the In-Reply-To: header
+	CH_UPDATE_REFS	update the References: header
 
    prefix
    	string to use if CH_PREFIX is set
@@ -335,6 +349,9 @@
 mutt_copy_header (FILE *in, HEADER *h, FILE *out, int flags, const char *prefix)
 {
   char buffer[SHORT_STRING];
+
+  flags |= (h->irt_changed ? CH_UPDATE_IRT : 0)
+         | (h->refs_changed ? CH_UPDATE_REFS : 0);
   
   if (mutt_copy_hdr (in, out, h->offset, h->content->offset, flags, prefix) == -1)
     return (-1);
@@ -358,7 +375,56 @@
   if (flags & CH_UPDATE)
   {
     if ((flags & CH_NOSTATUS) == 0)
+#ifdef IMAP_EDIT_THREADS
+#define NEW_ENV new_env
+#else
+#define NEW_ENV env
+#endif
     {
+      if (h->irt_changed && h->NEW_ENV->in_reply_to)
+      {
+	LIST *listp = h->NEW_ENV->in_reply_to;
+
+	if (fputs ("In-Reply-To: ", out) == EOF)
+	  return (-1);
+
+	for (; listp; listp = listp->next)
+	  if ((fputs (listp->data, out) == EOF) || (fputc (' ', out) == EOF))
+	    return (-1);
+
+	if (fputc ('\n', out) == EOF)
+	  return (-1);
+      }
+
+      if (h->refs_changed && h->NEW_ENV->references)
+      {
+	LIST *listp = h->NEW_ENV->references, *refs = NULL, *t;
+
+	if (fputs ("References: ", out) == EOF)
+	  return (-1);
+
+	/* Mutt stores references in reverse order, thus we create
+	 * a reordered refs list that we can put in the headers */
+	for (; listp; listp = listp->next, refs = t)
+	{
+	  t = (LIST *)safe_malloc (sizeof (LIST));
+	  t->data = listp->data;
+	  t->next = refs;
+	}
+
+	for (; refs; refs = refs->next)
+	  if ((fputs (refs->data, out) == EOF) || (fputc (' ', out) == EOF))
+	    return (-1);
+
+	/* clearing refs from memory */
+	for (t = refs; refs; refs = t->next, t = refs)
+	  safe_free ((void **)&refs);
+
+	if (fputc ('\n', out) == EOF)
+	  return (-1);
+      }
+#undef NEW_ENV
+
       if (h->old || h->read)
       {
 	if (fputs ("Status: ", out) == EOF)
diff -ru work.old/mutt-1.5.6/curs_main.c work/mutt-1.5.6/curs_main.c
--- curs_main.c	Wed Nov  5 10:41:31 2003
+++ curs_main.c	Tue Feb 10 14:40:41 2004
@@ -930,6 +930,11 @@
 	else
 	{
 	  mutt_set_flag (Context, CURHDR, M_TAG, !CURHDR->tagged);
+
+	  Context->last_tag = CURHDR->tagged ? CURHDR :
+	    ((Context->last_tag == CURHDR && !CURHDR->tagged)
+	     ? NULL : Context->last_tag);
+
 	  menu->redraw = REDRAW_STATUS;
 	  if (option (OPTRESOLVE) && menu->current < Context->vcount - 1)
 	  {
@@ -1162,6 +1167,89 @@
 	  }
 	  done = 1;
 	}
+	break;
+
+      case OP_MAIN_BREAK_THREAD:
+
+	CHECK_MSGCOUNT;
+        CHECK_VISIBLE;
+	CHECK_READONLY;
+
+        if ((Sort & SORT_MASK) != SORT_THREADS)
+	  mutt_error _("Threading is not enabled.");
+
+#if defined (USE_IMAP) && ! defined (IMAP_EDIT_THREADS)
+	else if (Context->magic == M_IMAP)
+	  mutt_error _("Compile Mutt with --enable-imap-edit-threads for break-thread support");
+#endif
+
+	else
+	{
+	  {
+	    HEADER *oldcur = CURHDR;
+
+	    mutt_break_thread (CURHDR);
+	    mutt_sort_headers (Context, 1);
+	    menu->current = oldcur->virtual;
+	  }
+
+	  Context->changed = 1;
+	  mutt_message _("Thread broken");
+
+	  if (menu->menu == MENU_PAGER)
+	  {
+	    op = OP_DISPLAY_MESSAGE;
+	    continue;
+	  }
+	  else
+	    menu->redraw |= REDRAW_INDEX;
+	}
+
+	  break;
+
+      case OP_MAIN_LINK_THREADS:
+
+	CHECK_MSGCOUNT;
+        CHECK_VISIBLE;
+	CHECK_READONLY;
+
+        if ((Sort & SORT_MASK) != SORT_THREADS)
+	  mutt_error _("Threading is not enabled.");
+
+#if defined (USE_IMAP) && ! defined (IMAP_EDIT_THREADS)
+	else if (Context->magic == M_IMAP)
+	  mutt_error _("Compile Mutt with --enable-imap-edit-threads for link-threads support");
+#endif
+
+	else if (!CURHDR->env->message_id)
+	  mutt_error _("No Message-ID: header available to link thread");
+	else if (!tag && (!Context->last_tag || !Context->last_tag->tagged))
+	  mutt_error _("First, please tag a message to be linked here");
+	else 
+	{
+	  HEADER *oldcur = CURHDR;
+
+	  if (mutt_link_threads (CURHDR, tag ? NULL : Context->last_tag,
+				 Context))
+	  {
+	    mutt_sort_headers (Context, 1);
+	    menu->current = oldcur->virtual;
+	    
+	    Context->changed = 1;
+	    mutt_message _("Threads linked");
+	  }
+	  else
+	    mutt_error _("No thread linked");
+	}
+
+	if (menu->menu == MENU_PAGER)
+	{
+	  op = OP_DISPLAY_MESSAGE;
+	  continue;
+	}
+	else
+	  menu->redraw |= REDRAW_STATUS | REDRAW_INDEX;
+
 	break;
 
       case OP_EDIT_TYPE:
diff -ru work.old/mutt-1.5.6/doc/manual.sgml.head work/mutt-1.5.6/doc/manual.sgml.head
--- doc/manual.sgml.head	Sun Feb  1 18:49:53 2004
+++ doc/manual.sgml.head	Tue Feb 10 14:40:41 2004
@@ -2197,8 +2197,43 @@
 with large volume mailing lists easier because you can easily delete
 uninteresting threads and quickly find topics of value.
 
+<sect1>Editing threads
+<p>
+Mutt has the ability to dynamically restructure threads that are broken
+either by misconfigured software or bad behaviour from some
+correspondents. This allows to clean your mailboxes formats) from these
+annoyances which make it hard to follow a discussion.
+
+If you want to use these functions with IMAP, you need to compile Mutt
+with the <em/--enable-imap-edit-threads/ configure flag.
+
+<sect2>Linking threads
+<p>
+
+Some mailers tend to "forget" to correctly set the "In-Reply-To:" and
+"References:" headers when replying to a message. This results in broken
+discussions because Mutt has not enough information to guess the correct
+threading.
+You can fix this by tagging the reply, then moving to the parent message
+and using the ``link-threads'' function (bound to & by default). The
+reply will then be connected to this "parent" message.
+
+You can also connect multiple childs at once, tagging them and using the
+tag-prefix command (';') or the auto_tag option.
+
+<sect2>Breaking threads
+<p>
+
+On mailing lists, some people are in the bad habit of starting a new
+discussion by hitting "reply" to any message from the list and changing
+the subject to a totally unrelated one.
+You can fix such threads by using the ``break-thread'' function (bound
+by default to #), which will turn the subthread starting from the
+current message into a whole different thread.
+
 <sect1>Delivery Status Notification (DSN) Support
 <p>
+
 RFC1894 defines a set of MIME content types for relaying information
 about the status of electronic mail messages.  These can be thought of as
 ``return receipts.'' Berkeley sendmail 8.8.x currently has some command
diff -ru work.old/mutt-1.5.6/functions.h work/mutt-1.5.6/functions.h
--- functions.h	Wed Nov  5 10:41:31 2003
+++ functions.h	Tue Feb 10 14:40:41 2004
@@ -69,6 +69,7 @@
 struct binding_t OpMain[] = {
   { "create-alias",		OP_CREATE_ALIAS,		"a" },
   { "bounce-message",		OP_BOUNCE_MESSAGE,		"b" },
+  { "break-thread",		OP_MAIN_BREAK_THREAD,		"#" },
   { "change-folder",		OP_MAIN_CHANGE_FOLDER,		"c" },
   { "change-folder-readonly",	OP_MAIN_CHANGE_FOLDER_READONLY,	"\033c" },
   { "collapse-thread",		OP_MAIN_COLLAPSE_THREAD,	"\033v" },
@@ -95,6 +96,7 @@
   { "next-undeleted",		OP_MAIN_NEXT_UNDELETED,		"j" },
   { "previous-undeleted",	OP_MAIN_PREV_UNDELETED,		"k" },
   { "limit",			OP_MAIN_LIMIT,			"l" },
+  { "link-threads",		OP_MAIN_LINK_THREADS,		"&" },
   { "list-reply",		OP_LIST_REPLY,			"L" },
   { "mail",			OP_MAIL,			"m" },
   { "toggle-new",		OP_TOGGLE_NEW,			"N" },
@@ -153,6 +155,7 @@
 };
 
 struct binding_t OpPager[] = {
+  { "break-thread",	OP_MAIN_BREAK_THREAD,		"#" },
   { "create-alias",	OP_CREATE_ALIAS,		"a" },
   { "bounce-message",	OP_BOUNCE_MESSAGE,		"b" },
   { "change-folder",	OP_MAIN_CHANGE_FOLDER,		"c" },
@@ -175,6 +178,7 @@
   { "next-entry",	OP_NEXT_ENTRY,			"J" },
   { "previous-undeleted",OP_MAIN_PREV_UNDELETED,	"k" },
   { "previous-entry",	OP_PREV_ENTRY,			"K" },
+  { "link-threads",	OP_MAIN_LINK_THREADS,		"&" },
   { "list-reply",	OP_LIST_REPLY,			"L" },
   { "redraw-screen",	OP_REDRAW,			"\014" },
   { "mail",		OP_MAIL,			"m" },
diff -ru work.old/mutt-1.5.6/imap/imap.c work/mutt-1.5.6/imap/imap.c
--- imap/imap.c	Sun Feb  1 18:10:58 2004
+++ imap/imap.c	Tue Feb 10 14:40:41 2004
@@ -981,9 +981,11 @@
       mutt_buffer_addstr (&cmd, "UID STORE ");
       mutt_buffer_addstr (&cmd, uid);
 
-      /* if attachments have been deleted we delete the message and reupload
-       * it. This works better if we're expunging, of course. */
-      if (ctx->hdrs[n]->attach_del)
+      /* if the message has been rethreaded or attachments have been deleted
+       * we delete the message and reupload it.
+       * This works better if we're expunging, of course. */
+      if (ctx->hdrs[n]->refs_changed || ctx->hdrs[n]->irt_changed ||
+	  ctx->hdrs[n]->attach_del)
       {
 	dprint (3, (debugfile, "imap_sync_mailbox: Attachments to be deleted, falling back to _mutt_save_message\n"));
 	if (!appendctx)
diff -ru work.old/mutt-1.5.6/main.c work/mutt-1.5.6/main.c
--- main.c	Tue Mar  4 08:49:48 2003
+++ main.c	Tue Feb 10 14:40:41 2004
@@ -228,6 +228,12 @@
         "-USE_IMAP  "
 #endif
 
+#ifdef IMAP_EDIT_THREADS
+        "+IMAP_EDIT_THREADS  "
+#else
+        "-IMAP_EDIT_THREADS  "
+#endif
+
 #ifdef USE_GSS
 	"+USE_GSS  "
 #else
diff -ru work.old/mutt-1.5.6/mh.c work/mutt-1.5.6/mh.c
--- mh.c	Sun Feb  1 18:10:57 2004
+++ mh.c	Tue Feb 10 14:40:41 2004
@@ -1220,7 +1220,7 @@
 {
   HEADER *h = ctx->hdrs[msgno];
 
-  if (h->attach_del)
+  if (h->attach_del || h->refs_changed || h->irt_changed)
     if (mh_rewrite_message (ctx, msgno) != 0)
       return -1;
 
@@ -1231,9 +1231,9 @@
 {
   HEADER *h = ctx->hdrs[msgno];
 
-  if (h->attach_del)
+  if (h->attach_del || h->refs_changed || h->irt_changed)
   {
-    /* when doing attachment deletion, fall back to the MH case. */
+    /* when doing attachment deletion/rethreading, fall back to the MH case. */
     if (mh_rewrite_message (ctx, msgno) != 0)
       return (-1);
   }
diff -ru work.old/mutt-1.5.6/mutt.h work/mutt-1.5.6/mutt.h
--- mutt.h	Sun Feb  1 18:15:17 2004
+++ mutt.h	Tue Feb 10 14:41:33 2004
@@ -94,6 +94,8 @@
 #define CH_WEED_DELIVERED (1<<13) /* weed eventual Delivered-To headers */
 #define CH_FORCE_FROM	(1<<14)	/* give CH_FROM precedence over CH_WEED? */
 #define CH_NOQFROM	(1<<15)	/* give CH_FROM precedence over CH_WEED? */
+#define CH_UPDATE_IRT	(1<<16) /* update In-Reply-To: */
+#define CH_UPDATE_REFS	(1<<17) /* update References: */
 
 /* flags for mutt_enter_string() */
 #define  M_ALIAS   1      /* do alias "completion" by calling up the alias-menu */
@@ -518,6 +520,8 @@
 void mutt_free_rx_list (RX_LIST **);
 int mutt_matches_ignore (const char *, LIST *);
 
+LIST *mutt_copy_list (LIST *);
+
 /* add an element to a list */
 LIST *mutt_add_list (LIST *, const char *);
 
@@ -657,6 +661,8 @@
   unsigned int subject_changed : 1; 	/* used for threading */
   unsigned int threaded : 1;	    	/* used for threading */
   unsigned int display_subject : 1; 	/* used for threading */
+  unsigned int irt_changed : 1; /* In-Reply-To changed to link/break threads */
+  unsigned int refs_changed : 1; /* References changed to break thread */
   unsigned int recip_valid : 1;  	/* is_recipient is valid */
   unsigned int active : 1;	    	/* message is not to be removed */
   unsigned int trash : 1;		/* message is marked as trashed on disk.
@@ -697,6 +703,10 @@
   char *tree;           	/* character string to print thread tree */
   struct thread *thread;
 
+#ifdef IMAP_EDIT_THREADS
+  ENVELOPE *new_env;	/* envelope information for rethreading */
+#endif
+
 #ifdef MIXMASTER
   LIST *chain;
 #endif
@@ -761,6 +771,7 @@
   char *pattern;                /* limit pattern string */
   pattern_t *limit_pattern;     /* compiled limit pattern */
   HEADER **hdrs;
+  HEADER *last_tag;		/* last tagged msg. used to link threads */
   THREAD *tree;			/* top of thread tree */
   HASH *id_hash;		/* hash table by msg id */
   HASH *subj_hash;		/* hash table by subject */
diff -ru work.old/mutt-1.5.6/mx.c work/mutt-1.5.6/mx.c
--- mx.c	Wed Nov  5 10:41:32 2003
+++ mx.c	Tue Feb 10 14:40:41 2004
@@ -1161,6 +1161,8 @@
         ctx->deleted = 0;
       }
     }
+    else if (ctx->last_tag && ctx->last_tag->deleted)
+      ctx->last_tag = NULL; /* reset last tagged msg now useless */
   }
 
   /* really only for IMAP - imap_sync_mailbox results in a call to
diff -ru work.old/mutt-1.5.6/pager.c work/mutt-1.5.6/pager.c
--- pager.c	Sun Feb  1 18:10:57 2004
+++ pager.c	Tue Feb 10 14:40:41 2004
@@ -2481,6 +2481,11 @@
       case OP_TAG:
 	CHECK_MODE(IsHeader (extra));
 	mutt_set_flag (Context, extra->hdr, M_TAG, !extra->hdr->tagged);
+
+	Context->last_tag = extra->hdr->tagged ? extra->hdr :
+	  ((Context->last_tag == extra->hdr && !extra->hdr->tagged)
+	   ? NULL : Context->last_tag);
+
 	redraw = REDRAW_STATUS | REDRAW_INDEX;
 	if (option (OPTRESOLVE))
 	{
diff -ru work.old/mutt-1.5.6/protos.h work/mutt-1.5.6/protos.h
--- protos.h	Sun Feb  1 18:15:17 2004
+++ protos.h	Tue Feb 10 14:40:41 2004
@@ -148,6 +148,7 @@
 void mutt_block_signals_system (void);
 void mutt_body_handler (BODY *, STATE *);
 int  mutt_bounce_message (FILE *fp, HEADER *, ADDRESS *);
+void mutt_break_thread (HEADER *);
 void mutt_buffy (char *, size_t);
 int  mutt_buffy_list (void);
 void mutt_canonical_charset (char *, size_t, const char *);
@@ -289,6 +290,7 @@
 int mutt_is_subscribed_list (ADDRESS *);
 int mutt_is_text_part (BODY *);
 int mutt_is_valid_mailbox (const char *);
+int mutt_link_threads (HEADER *, HEADER *, CONTEXT *);
 int mutt_lookup_mime_type (BODY *, const char *);
 int mutt_match_rx_list (const char *, RX_LIST *);
 int mutt_messages_in_thread (CONTEXT *, HEADER *, int);
diff -ru work.old/mutt-1.5.6/thread.c work/mutt-1.5.6/thread.c
--- thread.c	Sun Feb  1 18:10:58 2004
+++ thread.c	Tue Feb 10 14:40:41 2004
@@ -1336,3 +1336,105 @@
 
   return hash;
 }
+
+static void clean_references (THREAD *brk, THREAD *cur)
+{
+  THREAD *p;
+  LIST *ref = NULL;
+  int done = 0;
+
+  for (; cur; cur = cur->next, done = 0)
+  {
+    /* parse subthread recursively */
+    clean_references (brk, cur->child);
+
+    if (!cur->message)
+      break; /* skip pseudo-message */
+
+    /* Looking for the first bad reference according to the new threading.
+     * Optimal since Mutt stores the references in reverse order, and the
+     * first loop should match immediatly for mails respecting RFC2822. */
+    for (p = brk; !done && p; p = p->parent)
+      for (ref = cur->message->env->references; p->message && ref; ref = ref->next)
+	if (!mutt_strcasecmp (ref->data, p->message->env->message_id))
+	{
+	  done = 1;
+	  break;
+	}
+
+    if (done)
+    {
+      HEADER *h = cur->message;
+
+      /* clearing the References: header from obsolete Message-Id(s) */
+      mutt_free_list (&ref->next);
+
+#ifdef IMAP_EDIT_THREADS
+      if (h->new_env)
+	mutt_free_list (&h->new_env->references);
+      else
+	h->new_env = mutt_new_envelope ();
+
+      h->new_env->references = mutt_copy_list (h->env->references);
+#endif
+
+      h->refs_changed = h->changed = 1;
+    }
+  }
+}
+
+void mutt_break_thread (HEADER *hdr)
+{
+  mutt_free_list (&hdr->env->in_reply_to);
+  mutt_free_list (&hdr->env->references);
+  hdr->irt_changed = hdr->refs_changed = hdr->changed = 1;
+
+#ifdef IMAP_EDIT_THREADS
+  if (hdr->new_env)
+  {
+    mutt_free_list (&hdr->new_env->in_reply_to);
+    mutt_free_list (&hdr->new_env->references);
+  }
+  else
+    hdr->new_env = mutt_new_envelope ();
+#endif
+
+  clean_references (hdr->thread, hdr->thread->child);
+}
+
+static int link_threads (HEADER *parent, HEADER *child, CONTEXT *ctx)
+{
+  if (child == parent)
+    return 0;
+
+  mutt_break_thread (child);
+
+  child->env->in_reply_to = mutt_new_list ();
+  child->env->in_reply_to->data = safe_strdup (parent->env->message_id);
+
+#ifdef IMAP_EDIT_THREADS
+  child->new_env->in_reply_to = mutt_new_list ();
+  child->new_env->in_reply_to->data = safe_strdup (parent->env->message_id);
+#endif
+  
+  mutt_set_flag (ctx, child, M_TAG, 0);
+  
+  child->irt_changed = child->changed = 1;
+  return 1;
+}
+
+int mutt_link_threads (HEADER *cur, HEADER *last, CONTEXT *ctx)
+{
+  int i, changed = 0;
+
+  if (!last)
+  {
+    for (i = 0; i < ctx->vcount; i++)
+      if (ctx->hdrs[Context->v2r[i]]->tagged)
+	changed |= link_threads (cur, ctx->hdrs[Context->v2r[i]], ctx);
+  }
+  else
+    changed = link_threads (cur, last, ctx);
+
+  return changed;
+}