diff --git a/doc/en/weechat_plugin_api.en.adoc b/doc/en/weechat_plugin_api.en.adoc
index 9e4f8b8a3..c348c570d 100644
--- a/doc/en/weechat_plugin_api.en.adoc
+++ b/doc/en/weechat_plugin_api.en.adoc
@@ -10628,7 +10628,7 @@ hook = weechat.hook_connect("", "my.server.org", 1234, 1, 0, "",
 
 ==== hook_line
 
-_WeeChat ≥ 2.3, updated in 3.7._
+_WeeChat ≥ 2.3, updated in 3.7, 4.1.0._
 
 Hook a line to be printed in a buffer.
 
@@ -10699,13 +10699,13 @@ Line data sent to the callback is a hashtable, with following values
 | Key | Value (formatted buffer) | Value (free buffer) | Examples
 
 | buffer
-| Buffer pointer.
-| Buffer pointer.
+| Comma-separated list of buffer pointers.
+| Comma-separated list of buffer pointers.
 | `+0x1234abcd+`
 
 | buffer_name
-| Buffer name.
-| Buffer name.
+| Comma-separated list of buffer names.
+| Comma-separated list of buffer names.
 | `+core.weechat+` +
   `+irc.server.libera+` +
   `+irc.libera.#weechat+`
@@ -10793,16 +10793,20 @@ in this hashtable):
 | Key | Allowed value (formatted buffer) | Allowed value (free buffer) | Result
 
 | buffer
-| Pointer of a buffer with formatted content.
-| Pointer of a buffer with free content.
-| The line is displayed on this buffer. +
+| Comma-separated list buffer pointers (with formatted content)
+  (multiple buffers are supported only with WeeChat ≥ 4.1.0).
+| Comma-separated list buffer pointers (with free content)
+  (multiple buffers are supported only with WeeChat ≥ 4.1.0).
+| The line is displayed on these buffers. +
   If the value is empty, the line is deleted (anything else in the hashtable
   is then ignored); the next hooks of type "line" are not called.
 
 | buffer_name
-| Name of a buffer with formatted content.
-| Name of a buffer with free content.
-| The line is displayed on this buffer. +
+| Comma-separated list buffer names (with formatted content)
+  (multiple buffers are supported only with WeeChat ≥ 4.1.0).
+| Comma-separated list buffer names (with free content)
+  (multiple buffers are supported only with WeeChat ≥ 4.1.0).
+| The line is displayed on these buffers. +
   If `buffer` is also set, the value of `+buffer_name+` has higher priority and is used. +
   If the value is empty, the line is deleted (anything else in the hashtable
   is then ignored); the next hooks of type "line" are not called.
diff --git a/doc/fr/weechat_plugin_api.fr.adoc b/doc/fr/weechat_plugin_api.fr.adoc
index c0d52917a..957715cd3 100644
--- a/doc/fr/weechat_plugin_api.fr.adoc
+++ b/doc/fr/weechat_plugin_api.fr.adoc
@@ -10831,7 +10831,7 @@ hook = weechat.hook_connect("", "my.server.org", 1234, 1, 0, "",
 
 ==== hook_line
 
-_WeeChat ≥ 2.3, mis à jour dans la 3.7._
+_WeeChat ≥ 2.3, mis à jour dans la 3.7, 4.1.0._
 
 Intercepter une ligne sur le point d'être affichée dans un tampon.
 
@@ -10909,13 +10909,13 @@ de hachage, avec les valeurs suivantes (les clés et valeurs sont des chaînes)
 | Clé | Valeur (tampon formaté) | Valeur (tampon libre) | Exemples
 
 | buffer
-| Pointeur vers le tampon.
-| Pointeur vers le tampon.
+| Liste de pointeurs vers les tampons, séparés par des virgules.
+| Liste de pointeurs vers les tampons, séparés par des virgules.
 | `+0x1234abcd+`
 
 | buffer_name
-| Nom du tampon.
-| Nom du tampon.
+| Liste de noms de tampons, séparés par des virgules.
+| Liste de noms de tampons, séparés par des virgules.
 | `+core.weechat+` +
   `+irc.server.libera+` +
   `+irc.libera.#weechat+`
@@ -11004,16 +11004,20 @@ valeurs sont des chaînes dans cette table de hachage) :
 | Clé | Valeur autorisée (tampon formaté) | Valeur autorisée (tampon libre) | Résultat
 
 | buffer
-| Pointeur vers un tampon avec contenu formaté.
-| Pointeur vers un tampon avec contenu libre.
-| La ligne est affichée sur ce tampon. +
+| Liste de pointeurs vers les tampons, séparés par des virgules (avec contenu formaté)
+  (plusieurs tampons sont supportés seulement avec WeeChat ≥ 4.1.0).
+| Liste de pointeurs vers les tampons, séparés par des virgules (avec contenu libre)
+  (plusieurs tampons sont supportés seulement avec WeeChat ≥ 4.1.0).
+| La ligne est affichée sur ces tampons. +
   Si la valeur est vide, la ligne est supprimée (le reste de la table de hachage
   est alors ignoré) ; les "hooks" suivants de type "line" ne sont pas appelés.
 
 | buffer_name
-| Nom d'un tampon avec contenu formaté.
-| Nom d'un tampon avec contenu libre.
-| La ligne est affichée sur ce tampon. +
+| Liste de noms de tampons, séparés par des virgules (avec contenu formaté)
+  (multiple buffers are supported only with WeeChat ≥ 4.1.0).
+| Liste de noms de tampons, séparés par des virgules (avec contenu libre)
+  (multiple buffers are supported only with WeeChat ≥ 4.1.0).
+| La ligne est affichée sur ces tampons. +
   Si `buffer` est également défini, la valeur de `+buffer_name+` a une priorité
   plus haute est est utilisée. +
   Si la valeur est vide, la ligne est supprimée (le reste de la table de hachage
diff --git a/doc/it/weechat_plugin_api.it.adoc b/doc/it/weechat_plugin_api.it.adoc
index 4026f38c4..6cda03dbe 100644
--- a/doc/it/weechat_plugin_api.it.adoc
+++ b/doc/it/weechat_plugin_api.it.adoc
@@ -11016,7 +11016,7 @@ hook = weechat.hook_connect("", "my.server.org", 1234, 1, 0, "",
 // TRANSLATION MISSING
 ==== hook_line
 
-_WeeChat ≥ 2.3, updated in 3.7._
+_WeeChat ≥ 2.3, updated in 3.7, 4.1.0._
 
 Hook a line to be printed in a buffer.
 
@@ -11087,13 +11087,13 @@ Line data sent to the callback is a hashtable, with following values
 | Key | Value (formatted buffer) | Value (free buffer) | Examples
 
 | buffer
-| Buffer pointer.
-| Buffer pointer.
+| Comma-separated list of buffer pointers.
+| Comma-separated list of buffer pointers.
 | `+0x1234abcd+`
 
 | buffer_name
-| Buffer name.
-| Buffer name.
+| Comma-separated list of buffer names.
+| Comma-separated list of buffer names.
 | `+core.weechat+` +
   `+irc.server.libera+` +
   `+irc.libera.#weechat+`
@@ -11181,16 +11181,20 @@ in this hashtable):
 | Key | Allowed value (formatted buffer) | Allowed value (free buffer) | Result
 
 | buffer
-| Pointer of a buffer with formatted content.
-| Pointer of a buffer with free content.
-| The line is displayed on this buffer. +
+| Comma-separated list buffer pointers (with formatted content)
+  (multiple buffers are supported only with WeeChat ≥ 4.1.0).
+| Comma-separated list buffer pointers (with free content)
+  (multiple buffers are supported only with WeeChat ≥ 4.1.0).
+| The line is displayed on these buffers. +
   If the value is empty, the line is deleted (anything else in the hashtable
   is then ignored); the next hooks of type "line" are not called.
 
 | buffer_name
-| Name of a buffer with formatted content.
-| Name of a buffer with free content.
-| The line is displayed on this buffer. +
+| Comma-separated list buffer names (with formatted content)
+  (multiple buffers are supported only with WeeChat ≥ 4.1.0).
+| Comma-separated list buffer names (with free content)
+  (multiple buffers are supported only with WeeChat ≥ 4.1.0).
+| The line is displayed on these buffers. +
   If `buffer` is also set, the value of `+buffer_name+` has higher priority and is used. +
   If the value is empty, the line is deleted (anything else in the hashtable
   is then ignored); the next hooks of type "line" are not called.
diff --git a/doc/ja/weechat_plugin_api.ja.adoc b/doc/ja/weechat_plugin_api.ja.adoc
index bdc9d1908..94a4830e9 100644
--- a/doc/ja/weechat_plugin_api.ja.adoc
+++ b/doc/ja/weechat_plugin_api.ja.adoc
@@ -10741,7 +10741,7 @@ hook = weechat.hook_connect("", "my.server.org", 1234, 1, 0, "",
 ==== hook_line
 
 // TRANSLATION MISSING
-_WeeChat ≥ 2.3, updated in 3.7._
+_WeeChat ≥ 2.3, updated in 3.7, 4.1.0._
 
 バッファに対する行表示をフックする。
 
@@ -10811,14 +10811,16 @@ struct t_hook *weechat_hook_line (const char *buffer_type,
 |===
 | キー | 値 (フォーマット済みバッファ) | 値 (自由内容バッファ) | 例
 
+// TRANSLATION MISSING
 | buffer
-| バッファポインタ
-| バッファポインタ
+| Comma-separated list of buffer pointers.
+| Comma-separated list of buffer pointers.
 | `+0x1234abcd+`
 
+// TRANSLATION MISSING
 | buffer_name
-| バッファ名
-| バッファ名
+| Comma-separated list of buffer names.
+| Comma-separated list of buffer names.
 | `+core.weechat+` +
   `+irc.server.libera+` +
   `+irc.libera.#weechat+`
@@ -10906,17 +10908,23 @@ WeeChat はそれらを無視します。
 |===
 | キー | 設定可能な値 (フォーマット済みバッファ) | 設定可能な値 (自由内容バッファ) | 結果
 
+// TRANSLATION MISSING
 | buffer
-| フォーマット済みバッファへのポインタ
-| 自由内容バッファへのポインタ
-| 行を表示するバッファ。 +
+| Comma-separated list buffer pointers (with formatted content)
+  (multiple buffers are supported only with WeeChat ≥ 4.1.0).
+| Comma-separated list buffer pointers (with free content)
+  (multiple buffers are supported only with WeeChat ≥ 4.1.0).
+| The line is displayed on these buffers. +
   この値が空の場合、行は削除されます (ハッシュテーブルに含まれるその他の情報も無視されます);
   "line" 型の次のフックも呼び出されません。
 
+// TRANSLATION MISSING
 | buffer_name
-| フォーマット済み内容バッファの名前.
-| 自由内容バッファの名前
-| 行を表示するバッファ。 +
+| Comma-separated list buffer names (with formatted content)
+  (multiple buffers are supported only with WeeChat ≥ 4.1.0).
+| Comma-separated list buffer names (with free content)
+  (multiple buffers are supported only with WeeChat ≥ 4.1.0).
+| The line is displayed on these buffers. +
   `buffer` と `+buffer_name+` の両方が設定された場合、`+buffer_name+` の値が優先されます +
   この値が空の場合、行は削除されます (ハッシュテーブルに含まれるその他の情報も無視されます);
   "line" 型の次のフックも呼び出されません。
diff --git a/doc/sr/weechat_plugin_api.sr.adoc b/doc/sr/weechat_plugin_api.sr.adoc
index fa26cfc82..1b600e3fc 100644
--- a/doc/sr/weechat_plugin_api.sr.adoc
+++ b/doc/sr/weechat_plugin_api.sr.adoc
@@ -10293,7 +10293,7 @@ hook = weechat.hook_connect("", "my.server.org", 1234, 1, 0, "",
 
 ==== hook_line
 
-_WeeChat ≥ 2.3, ажурирано у 3.7._
+_WeeChat ≥ 2.3, ажурирано у 3.7, 4.1.0._
 
 Качи се на линију која треба да се испише у бафер.
 
@@ -10349,14 +10349,16 @@ struct t_hook *weechat_hook_line (const char *buffer_type,
 |===
 | Кључ | Вредност (форматирани бафер) | Вредност (слободни бафер) | Примери
 
+// TRANSLATION MISSING
 | buffer
-| Показивач на бафер.
-| Показивач на бафер.
+| Comma-separated list of buffer pointers.
+| Comma-separated list of buffer pointers.
 | `+0x1234abcd+`
 
+// TRANSLATION MISSING
 | buffer_name
-| Име бафера.
-| Име бафера.
+| Comma-separated list of buffer names.
+| Comma-separated list of buffer names.
 | `+core.weechat+` +
   `+irc.server.libera+` +
   `+irc.libera.#weechat+`
@@ -10441,17 +10443,23 @@ struct t_hook *weechat_hook_line (const char *buffer_type,
 |===
 | Кључ | Дозвољена вредност (форматирани бафер) | Дозвољена вредност (слободни бафер) | Резултат
 
+// TRANSLATION MISSING
 | buffer
-| Показивач на бафер са форматираним садржајем.
-| Показивач на бафер са слободним садржајем.
-| Линија се приказује у овом баферу. +
+| Comma-separated list buffer pointers (with formatted content)
+  (multiple buffers are supported only with WeeChat ≥ 4.1.0).
+| Comma-separated list buffer pointers (with free content)
+  (multiple buffers are supported only with WeeChat ≥ 4.1.0).
+| The line is displayed on these buffers. +
   Ако је вредност празна, линија се брише (тада се све остало у хеш табели
   игнорише); наредне куке типа „line” се не позивају.
 
+// TRANSLATION MISSING
 | buffer_name
-| Име бафера са форматираним садржајем.
-| Име бафера са слободним садржајем.
-| Линија се приказује у овом баферу. +
+| Comma-separated list buffer names (with formatted content)
+  (multiple buffers are supported only with WeeChat ≥ 4.1.0).
+| Comma-separated list buffer names (with free content)
+  (multiple buffers are supported only with WeeChat ≥ 4.1.0).
+| The line is displayed on these buffers. +
   Ако је и `buffer` постављено, вредност `+buffer_name+` има виши приоритет и она се користи. +
   Ако је вредност празна, линија се брише (тада се све остало у хеш табели
   игнорише); наредне куке типа „line” се не позивају.
diff --git a/src/core/hook/wee-hook-line.c b/src/core/hook/wee-hook-line.c
index 6b3305fc4..3894df59b 100644
--- a/src/core/hook/wee-hook-line.c
+++ b/src/core/hook/wee-hook-line.c
@@ -27,6 +27,7 @@
 #include <string.h>
 
 #include "../weechat.h"
+#include "../wee-arraylist.h"
 #include "../wee-hashtable.h"
 #include "../wee-hook.h"
 #include "../wee-infolist.h"
@@ -121,17 +122,31 @@ hook_line (struct t_weechat_plugin *plugin, const char *buffer_type,
  * Executes a line hook and updates the line data.
  */
 
-void
+struct t_arraylist *
 hook_line_exec (struct t_gui_line *line)
 {
     struct t_hook *ptr_hook, *next_hook;
     struct t_hashtable *hashtable, *hashtable2;
-    char str_value[128], *str_tags;
-
-    if (!weechat_hooks[HOOK_TYPE_LINE])
-        return;
+    struct t_arraylist *buffers;
+    struct t_gui_buffer *ptr_buffer;
+    char str_value[128], *str_tags, **str_buffers;
+    int i, size;
 
     hashtable = NULL;
+    buffers = NULL;
+    str_buffers = NULL;
+
+    buffers = arraylist_new (16, 0, 0, NULL, NULL, NULL, NULL);
+    if (!buffers)
+        goto end;
+    arraylist_add (buffers, line->data->buffer);
+
+    if (!weechat_hooks[HOOK_TYPE_LINE])
+        goto end;
+
+    str_buffers = string_dyn_alloc (256);
+    if (!str_buffers)
+        goto end;
 
     hook_exec_start ();
 
@@ -161,8 +176,28 @@ hook_line_exec (struct t_gui_line *line)
                 if (!hashtable)
                     break;
             }
-            HASHTABLE_SET_POINTER("buffer", line->data->buffer);
-            HASHTABLE_SET_STR("buffer_name", line->data->buffer->full_name);
+            size = arraylist_size (buffers);
+            /* build list of buffer pointers */
+            string_dyn_copy (str_buffers, NULL);
+            for (i = 0; i < size; i++)
+            {
+                if (i > 0)
+                    string_dyn_concat (str_buffers, ",", -1);
+                snprintf (str_value, sizeof (str_value),
+                          "0x%lx", (unsigned long)(arraylist_get (buffers, i)));
+                string_dyn_concat (str_buffers, str_value, -1);
+            }
+            HASHTABLE_SET_STR("buffer", *str_buffers);
+            /* build list of buffer names */
+            string_dyn_copy (str_buffers, NULL);
+            for (i = 0; i < size; i++)
+            {
+                if (i > 0)
+                    string_dyn_concat (str_buffers, ",", -1);
+                ptr_buffer = (struct t_gui_buffer *)arraylist_get (buffers, i);
+                string_dyn_concat (str_buffers, ptr_buffer->full_name, -1);
+            }
+            HASHTABLE_SET_STR("buffer_name", *str_buffers);
             HASHTABLE_SET_STR("buffer_type",
                               gui_buffer_type_string[line->data->buffer->type]);
             HASHTABLE_SET_INT("y", line->data->y);
@@ -191,7 +226,7 @@ hook_line_exec (struct t_gui_line *line)
 
             if (hashtable2)
             {
-                gui_line_hook_update (line, hashtable, hashtable2);
+                gui_line_hook_update (line, buffers, hashtable, hashtable2);
                 hashtable_free (hashtable2);
                 if (!line->data->buffer)
                     break;
@@ -203,8 +238,17 @@ hook_line_exec (struct t_gui_line *line)
 
     hook_exec_end ();
 
+end:
     if (hashtable)
         hashtable_free (hashtable);
+
+    if (str_buffers)
+        string_dyn_free (str_buffers, 1);
+
+    if (line->data->buffer && buffers && (arraylist_size (buffers) == 0))
+        arraylist_add (buffers, line->data->buffer);
+
+    return buffers;
 }
 
 /*
diff --git a/src/core/hook/wee-hook-line.h b/src/core/hook/wee-hook-line.h
index 9d6160f54..470c8ca23 100644
--- a/src/core/hook/wee-hook-line.h
+++ b/src/core/hook/wee-hook-line.h
@@ -51,7 +51,7 @@ extern struct t_hook *hook_line (struct t_weechat_plugin *plugin,
                                  t_hook_callback_line *callback,
                                  const void *callback_pointer,
                                  void *callback_data);
-extern void hook_line_exec (struct t_gui_line *line);
+extern struct t_arraylist *hook_line_exec (struct t_gui_line *line);
 extern void hook_line_free_data (struct t_hook *hook);
 extern int hook_line_add_to_infolist (struct t_infolist_item *item,
                                       struct t_hook *hook);
diff --git a/src/gui/gui-chat.c b/src/gui/gui-chat.c
index 0eb3d168c..70e5c7de9 100644
--- a/src/gui/gui-chat.c
+++ b/src/gui/gui-chat.c
@@ -32,6 +32,7 @@
 #include <regex.h>
 
 #include "../core/weechat.h"
+#include "../core/wee-arraylist.h"
 #include "../core/wee-config.h"
 #include "../core/wee-eval.h"
 #include "../core/wee-hashtable.h"
@@ -592,15 +593,18 @@ gui_chat_printf_date_tags_internal (struct t_gui_buffer *buffer,
                                     const char *tags,
                                     char *message)
 {
-    int display_time, length_data, length_str;
+    int i, display_time, length_data, length_str, num_buffers;
     char *ptr_msg, *pos_prefix, *pos_tab;
     char *modifier_data, *string, *new_string, *pos_newline;
-    struct t_gui_line *new_line;
+    struct t_gui_line *new_line, *new_line2;
+    struct t_arraylist *buffers;
 
     new_line = NULL;
+    new_line2 = NULL;
     string = NULL;
     modifier_data = NULL;
     new_string = NULL;
+    buffers = NULL;
 
     display_time = 1;
 
@@ -643,134 +647,132 @@ gui_chat_printf_date_tags_internal (struct t_gui_buffer *buffer,
     if (!new_line)
         goto no_print;
 
-    hook_line_exec (new_line);
-
-    if (!new_line->data->buffer)
+    buffers = hook_line_exec (new_line);
+    if (!buffers || !new_line->data->buffer)
         goto no_print;
 
-    /* call modifier for message printed ("weechat_print") */
-    length_data = 64 + 1 + ((tags) ? strlen (tags) : 0) + 1;
-    modifier_data = malloc (length_data);
-    length_str = ((new_line->data->prefix && new_line->data->prefix[0]) ? strlen (new_line->data->prefix) : 1) +
-        1 +
-        (new_line->data->message ? strlen (new_line->data->message) : 0) +
-        1;
-    string = malloc (length_str);
-    if (modifier_data && string)
+    num_buffers = arraylist_size (buffers);
+    for (i = 0; i < num_buffers; i++)
     {
-        snprintf (modifier_data, length_data,
-                  "0x%lx;%s",
-                  (unsigned long)buffer,
-                  (tags) ? tags : "");
-        if (display_time)
-        {
-            snprintf (string, length_str,
-                      "%s\t%s",
-                      (new_line->data->prefix && new_line->data->prefix[0]) ?
-                      new_line->data->prefix : " ",
-                      (new_line->data->message) ? new_line->data->message : "");
-        }
-        else
-        {
-            snprintf (string, length_str,
-                      "\t\t%s",
-                      (new_line->data->message) ? new_line->data->message : "");
-        }
-        new_string = hook_modifier_exec (NULL,
-                                         "weechat_print",
-                                         modifier_data,
-                                         string);
-        if (new_string)
-        {
-            if (!new_string[0] && string[0])
-            {
-                /*
-                 * modifier returned empty message, then we'll not
-                 * print anything
-                 */
-                goto no_print;
-            }
-            else if (strcmp (string, new_string) != 0)
-            {
-                if (!buffer->input_multiline)
-                {
-                    /* if input_multiline is not set, keep only first line */
-                    pos_newline = strchr (new_string, '\n');
-                    if (pos_newline)
-                        pos_newline[0] = '\0';
-                }
+        new_line2 = gui_line_dup_for_buffer (new_line,
+                                             arraylist_get (buffers, i));
+        if (!new_line2)
+            goto no_print;
 
-                /* use new message if there are changes */
-                display_time = 1;
-                pos_prefix = NULL;
-                ptr_msg = new_string;
-                /* space followed by tab => prefix ignored */
-                if ((ptr_msg[0] == ' ') && (ptr_msg[1] == '\t'))
+        /* call modifier for message printed ("weechat_print") */
+        length_data = 64 + 1 + ((tags) ? strlen (tags) : 0) + 1;
+        modifier_data = malloc (length_data);
+        length_str = ((new_line2->data->prefix && new_line2->data->prefix[0]) ? strlen (new_line2->data->prefix) : 1) +
+            1 +
+            (new_line2->data->message ? strlen (new_line2->data->message) : 0) +
+            1;
+        string = malloc (length_str);
+        if (modifier_data && string)
+        {
+            snprintf (modifier_data, length_data,
+                      "0x%lx;%s",
+                      (unsigned long)buffer,
+                      (tags) ? tags : "");
+            if (display_time)
+            {
+                snprintf (string, length_str,
+                          "%s\t%s",
+                          (new_line2->data->prefix && new_line2->data->prefix[0]) ?
+                          new_line2->data->prefix : " ",
+                          (new_line2->data->message) ? new_line2->data->message : "");
+            }
+            else
+            {
+                snprintf (string, length_str,
+                          "\t\t%s",
+                          (new_line2->data->message) ? new_line2->data->message : "");
+            }
+            new_string = hook_modifier_exec (NULL,
+                                             "weechat_print",
+                                             modifier_data,
+                                             string);
+            if (new_string)
+            {
+                if (!new_string[0] && string[0])
                 {
-                    ptr_msg += 2;
+                    /*
+                     * modifier returned empty message, then we'll not
+                     * print anything
+                     */
+                    goto no_print;
                 }
-                else
+                else if (strcmp (string, new_string) != 0)
                 {
-                    /* if two first chars are tab, then do not display time */
-                    if ((ptr_msg[0] == '\t') && (ptr_msg[1] == '\t'))
+                    if (!buffer->input_multiline)
+                    {
+                        /* if input_multiline is not set, keep only first line */
+                        pos_newline = strchr (new_string, '\n');
+                        if (pos_newline)
+                            pos_newline[0] = '\0';
+                    }
+
+                    /* use new message if there are changes */
+                    display_time = 1;
+                    pos_prefix = NULL;
+                    ptr_msg = new_string;
+                    /* space followed by tab => prefix ignored */
+                    if ((ptr_msg[0] == ' ') && (ptr_msg[1] == '\t'))
                     {
-                        display_time = 0;
-                        new_line->data->date = 0;
                         ptr_msg += 2;
                     }
                     else
                     {
-                        /* if tab found, use prefix (before tab) */
-                        pos_tab = strchr (ptr_msg, '\t');
-                        if (pos_tab)
+                        /* if two first chars are tab, then do not display time */
+                        if ((ptr_msg[0] == '\t') && (ptr_msg[1] == '\t'))
                         {
-                            pos_tab[0] = '\0';
-                            pos_prefix = ptr_msg;
-                            ptr_msg = pos_tab + 1;
+                            display_time = 0;
+                            new_line2->data->date = 0;
+                            ptr_msg += 2;
+                        }
+                        else
+                        {
+                            /* if tab found, use prefix (before tab) */
+                            pos_tab = strchr (ptr_msg, '\t');
+                            if (pos_tab)
+                            {
+                                pos_tab[0] = '\0';
+                                pos_prefix = ptr_msg;
+                                ptr_msg = pos_tab + 1;
+                            }
                         }
                     }
+                    if ((new_line2->data->date == 0) && display_time)
+                        new_line2->data->date = new_line2->data->date_printed;
+                    if (new_line2->data->prefix)
+                        string_shared_free (new_line2->data->prefix);
+                    if (pos_prefix)
+                    {
+                        new_line2->data->prefix = (char *)string_shared_get (pos_prefix);
+                    }
+                    else
+                    {
+                        new_line2->data->prefix = (new_line2->data->date != 0) ?
+                            (char *)string_shared_get ("") : NULL;
+                    }
+                    new_line2->data->prefix_length = gui_chat_strlen_screen (
+                        new_line2->data->prefix);
+                    if (new_line2->data->message)
+                        free (new_line2->data->message);
+                    new_line2->data->message = strdup (ptr_msg);
                 }
-                if ((new_line->data->date == 0) && display_time)
-                    new_line->data->date = new_line->data->date_printed;
-                if (new_line->data->prefix)
-                    string_shared_free (new_line->data->prefix);
-                if (pos_prefix)
-                {
-                    new_line->data->prefix = (char *)string_shared_get (pos_prefix);
-                }
-                else
-                {
-                    new_line->data->prefix = (new_line->data->date != 0) ?
-                        (char *)string_shared_get ("") : NULL;
-                }
-                new_line->data->prefix_length = gui_chat_strlen_screen (
-                    new_line->data->prefix);
-                if (new_line->data->message)
-                    free (new_line->data->message);
-                new_line->data->message = strdup (ptr_msg);
             }
         }
+
+        /* add line in the buffer */
+        gui_line_add (new_line2);
+
+        /* run hook_print for the new line */
+        if (new_line2->data->buffer && new_line2->data->buffer->print_hooks_enabled)
+            hook_print_exec (new_line2->data->buffer, new_line2);
+
+        gui_buffer_ask_chat_refresh (new_line2->data->buffer, 1);
     }
 
-    /* add line in the buffer */
-    gui_line_add (new_line);
-
-    /* run hook_print for the new line */
-    if (new_line->data->buffer && new_line->data->buffer->print_hooks_enabled)
-        hook_print_exec (new_line->data->buffer, new_line);
-
-    gui_buffer_ask_chat_refresh (new_line->data->buffer, 1);
-
-    if (string)
-        free (string);
-    if (modifier_data)
-        free (modifier_data);
-    if (new_string)
-        free (new_string);
-
-    return;
-
-no_print:
     if (new_line)
     {
         gui_line_free_data (new_line);
@@ -782,6 +784,30 @@ no_print:
         free (modifier_data);
     if (new_string)
         free (new_string);
+    if (buffers)
+        arraylist_free (buffers);
+
+    return;
+
+no_print:
+    if (new_line)
+    {
+        gui_line_free_data (new_line);
+        free (new_line);
+    }
+    if (new_line2)
+    {
+        gui_line_free_data (new_line2);
+        free (new_line2);
+    }
+    if (string)
+        free (string);
+    if (modifier_data)
+        free (modifier_data);
+    if (new_string)
+        free (new_string);
+    if (buffers)
+        arraylist_free (buffers);
 }
 
 /*
@@ -932,9 +958,13 @@ void
 gui_chat_printf_y_date_tags (struct t_gui_buffer *buffer, int y, time_t date,
                            const char *tags, const char *message, ...)
 {
-    struct t_gui_line *ptr_line, *new_line, *new_line_empty;
+    struct t_gui_line *ptr_line, *new_line, *new_line2, *new_line_empty;
+    struct t_arraylist *buffers;
     time_t date_printed;
-    int i, last_y, num_lines_to_add;
+    int i, last_y, num_lines_to_add, num_buffers;
+
+    new_line = NULL;
+    buffers = NULL;
 
     if (!message)
         return;
@@ -964,84 +994,96 @@ gui_chat_printf_y_date_tags (struct t_gui_buffer *buffer, int y, time_t date,
     if (!new_line)
         goto end;
 
-    hook_line_exec (new_line);
-
-    if (!new_line->data->buffer)
+    buffers = hook_line_exec (new_line);
+    if (!buffers || !new_line->data->buffer)
     {
         gui_line_free_data (new_line);
         free (new_line);
         goto end;
     }
 
-    if (new_line->data->message && new_line->data->message[0])
+    num_buffers = arraylist_size (buffers);
+    for (i = 0; i < num_buffers; i++)
     {
-        if (gui_init_ok)
+        new_line2 = gui_line_dup_for_buffer (new_line,
+                                             arraylist_get (buffers, i));
+        if (new_line2->data->message && new_line2->data->message[0])
         {
-            /* compute the number of lines to add before y */
-            if (new_line->data->buffer->own_lines
-                && new_line->data->buffer->own_lines->last_line)
+            if (gui_init_ok)
             {
-                num_lines_to_add = y - new_line->data->buffer->own_lines->last_line->data->y - 1;
+                /* compute the number of lines to add before y */
+                if (new_line2->data->buffer->own_lines
+                    && new_line2->data->buffer->own_lines->last_line)
+                {
+                    num_lines_to_add = y - new_line2->data->buffer->own_lines->last_line->data->y - 1;
+                }
+                else
+                {
+                    num_lines_to_add = y;
+                }
+                if (num_lines_to_add > 0)
+                {
+                    /*
+                     * add empty line(s) before asked line, to ensure there is at
+                     * least "y" lines in buffer, and then be able to scroll
+                     * properly buffer page by page
+                     */
+                    for (i = y - num_lines_to_add; i < y; i++)
+                    {
+                        new_line_empty = gui_line_new (new_line2->data->buffer,
+                                                       i, 0, 0, NULL, NULL, "");
+                        if (new_line_empty)
+                            gui_line_add_y (new_line_empty);
+                    }
+                }
+                gui_line_add_y (new_line2);
             }
             else
             {
-                num_lines_to_add = y;
+                string_fprintf (stdout, "%s\n", new_line2->data->message);
+                gui_line_free_data (new_line2);
+                free (new_line2);
             }
-            if (num_lines_to_add > 0)
-            {
-                /*
-                 * add empty line(s) before asked line, to ensure there is at
-                 * least "y" lines in buffer, and then be able to scroll
-                 * properly buffer page by page
-                 */
-                for (i = y - num_lines_to_add; i < y; i++)
-                {
-                    new_line_empty = gui_line_new (new_line->data->buffer,
-                                                   i, 0, 0, NULL, NULL, "");
-                    if (new_line_empty)
-                        gui_line_add_y (new_line_empty);
-                }
-            }
-            gui_line_add_y (new_line);
         }
         else
         {
-            string_fprintf (stdout, "%s\n", new_line->data->message);
-            gui_line_free_data (new_line);
-            free (new_line);
-        }
-    }
-    else
-    {
-        if (gui_init_ok)
-        {
-            /* delete line */
-            last_y = (new_line->data->buffer->own_lines->last_line) ?
-                new_line->data->buffer->own_lines->last_line->data->y : 0;
-            if (y <= last_y)
+            if (gui_init_ok)
             {
-                for (ptr_line = new_line->data->buffer->own_lines->first_line;
-                     ptr_line; ptr_line = ptr_line->next_line)
+                /* delete line */
+                last_y = (new_line2->data->buffer->own_lines->last_line) ?
+                    new_line2->data->buffer->own_lines->last_line->data->y : 0;
+                if (y <= last_y)
                 {
-                    if (ptr_line->data->y >= y)
-                        break;
-                }
-                if (ptr_line && (ptr_line->data->y == y))
-                {
-                    if (ptr_line->next_line)
-                        gui_line_clear (ptr_line);
-                    else
-                        gui_line_free (new_line->data->buffer, ptr_line);
-                    gui_buffer_ask_chat_refresh (new_line->data->buffer, 2);
+                    for (ptr_line = new_line2->data->buffer->own_lines->first_line;
+                         ptr_line; ptr_line = ptr_line->next_line)
+                    {
+                        if (ptr_line->data->y >= y)
+                            break;
+                    }
+                    if (ptr_line && (ptr_line->data->y == y))
+                    {
+                        if (ptr_line->next_line)
+                            gui_line_clear (ptr_line);
+                        else
+                            gui_line_free (new_line2->data->buffer, ptr_line);
+                        gui_buffer_ask_chat_refresh (new_line2->data->buffer, 2);
+                    }
                 }
             }
+            gui_line_free_data (new_line2);
+            free (new_line2);
         }
-        gui_line_free_data (new_line);
-        free (new_line);
     }
 
 end:
+    if (new_line)
+    {
+        gui_line_free_data (new_line);
+        free (new_line);
+    }
     free (vbuffer);
+    if (buffers)
+        arraylist_free (buffers);
 }
 
 /*
diff --git a/src/gui/gui-line.c b/src/gui/gui-line.c
index efef30959..0b578a18a 100644
--- a/src/gui/gui-line.c
+++ b/src/gui/gui-line.c
@@ -30,6 +30,7 @@
 #include <regex.h>
 
 #include "../core/weechat.h"
+#include "../core/wee-arraylist.h"
 #include "../core/wee-config.h"
 #include "../core/wee-hashtable.h"
 #include "../core/wee-hdata.h"
@@ -112,6 +113,45 @@ gui_line_tags_alloc (struct t_gui_line_data *line_data, const char *tags)
     }
 }
 
+/*
+ * Duplicates array with tags of a line into another line.
+ */
+
+void
+gui_line_tags_dup (struct t_gui_line_data *line_data,
+                   struct t_gui_line_data *line_data2)
+{
+    int i;
+
+    if (!line_data || !line_data2)
+        return;
+
+    if (line_data->tags_count > 0)
+    {
+        line_data2->tags_array = malloc (
+            (line_data->tags_count + 1) * sizeof (*(line_data->tags_array)));
+        if (line_data2->tags_array)
+        {
+            line_data2->tags_count = line_data->tags_count;
+            for (i = 0; i < line_data->tags_count; i++)
+            {
+                line_data2->tags_array[i] = (char *)string_shared_get (
+                    line_data->tags_array[i]);
+            }
+            line_data2->tags_array[line_data->tags_count] = NULL;
+        }
+        else
+        {
+            line_data2->tags_count = 0;
+        }
+    }
+    else
+    {
+        line_data2->tags_count = 0;
+        line_data2->tags_array = NULL;
+    }
+}
+
 /*
  * Frees array with tags in a line_data.
  */
@@ -1561,12 +1601,96 @@ gui_line_new (struct t_gui_buffer *buffer, int y, time_t date,
     return new_line;
 }
 
+/*
+ * Duplicates a line to print it on another buffer.
+ */
+
+struct t_gui_line *
+gui_line_dup_for_buffer (struct t_gui_line *line, struct t_gui_buffer *buffer)
+{
+    struct t_gui_line *new_line;
+    struct t_gui_line_data *new_line_data;
+
+    if (!line || !buffer)
+        return NULL;
+
+    /* create new line */
+    new_line = malloc (sizeof (*new_line));
+    if (!new_line)
+        return NULL;
+
+    /* create data for line */
+    new_line_data = malloc (sizeof (*new_line_data));
+    if (!new_line_data)
+    {
+        free (new_line);
+        return NULL;
+    }
+    new_line->data = new_line_data;
+
+    /* fill data in new line */
+    new_line->data->buffer = buffer;
+    new_line->data->message = (line->data->message) ?
+        strdup (line->data->message) : strdup ("");
+
+    if (buffer->type == GUI_BUFFER_TYPE_FORMATTED)
+    {
+        /*
+         * the line identifier is almost unique: when reaching INT_MAX, it is
+         * reset to 0; it is extremely unlikely all integer are used in the
+         * same buffer, that would mean the buffer has a huge number of lines;
+         * when searching a line id in a buffer, it is recommended to start
+         * from the last line and loop to the first
+         */
+        new_line->data->id = buffer->next_line_id;
+        buffer->next_line_id = (buffer->next_line_id == INT_MAX) ?
+            0 : buffer->next_line_id + 1;
+        new_line->data->y = line->data->y;
+        new_line->data->date = line->data->date;
+        new_line->data->date_printed = line->data->date_printed;
+        new_line->data->str_time = (line->data->str_time) ?
+            strdup (line->data->str_time) : NULL;
+        gui_line_tags_dup (line->data, new_line->data);
+        new_line->data->refresh_needed = line->data->refresh_needed;
+        new_line->data->prefix = (line->data->prefix) ?
+            (char *)string_shared_get (line->data->prefix) : NULL;
+        new_line->data->prefix_length = line->data->prefix_length;
+        new_line->data->notify_level = line->data->notify_level;
+        new_line->data->highlight = line->data->highlight;
+    }
+    else
+    {
+        new_line->data->id = line->data->y;
+        new_line->data->y = line->data->y;
+        new_line->data->date = line->data->date;
+        new_line->data->date_printed = line->data->date_printed;
+        new_line->data->str_time = (line->data->str_time) ?
+            strdup (line->data->str_time) : NULL;
+        gui_line_tags_dup (line->data, new_line->data);
+        new_line->data->refresh_needed = line->data->refresh_needed;
+        new_line->data->prefix = (line->data->prefix) ?
+            (char *)string_shared_get (line->data->prefix) : NULL;
+        new_line->data->prefix_length = line->data->prefix_length;
+        new_line->data->notify_level = line->data->notify_level;
+        new_line->data->highlight = line->data->highlight;
+    }
+
+    /* set display flag (check if line is filtered or not) */
+    new_line->data->displayed = gui_filter_check_line (new_line->data);
+
+    new_line->prev_line = NULL;
+    new_line->next_line = NULL;
+
+    return new_line;
+}
+
 /*
  * Updates data in a line via the hook_line.
  */
 
 void
 gui_line_hook_update (struct t_gui_line *line,
+                      struct t_arraylist *buffers,
                       struct t_hashtable *hashtable,
                       struct t_hashtable *hashtable2)
 {
@@ -1574,9 +1698,9 @@ gui_line_hook_update (struct t_gui_line *line,
     struct t_gui_buffer *ptr_buffer;
     unsigned long value_pointer;
     long value;
-    char *error, *new_message, *pos_newline;
-    int rc, tags_updated, notify_level_updated, highlight_updated;
-    int max_notify_level;
+    char *error, *new_message, *pos_newline, **list_buffers;
+    int i, rc, tags_updated, notify_level_updated, highlight_updated;
+    int max_notify_level, num_buffers;
 
     tags_updated = 0;
     notify_level_updated = 0;
@@ -1587,12 +1711,30 @@ gui_line_hook_update (struct t_gui_line *line,
     {
         if (ptr_value2[0])
         {
-            ptr_buffer = gui_buffer_search_by_full_name (ptr_value2);
-            if (gui_chat_buffer_valid (ptr_buffer, line->data->buffer->type))
-                line->data->buffer = ptr_buffer;
+            list_buffers = string_split (
+                ptr_value2, ",", NULL,
+                WEECHAT_STRING_SPLIT_STRIP_LEFT
+                | WEECHAT_STRING_SPLIT_STRIP_RIGHT
+                | WEECHAT_STRING_SPLIT_COLLAPSE_SEPS,
+                0, &num_buffers);
+            if (list_buffers)
+            {
+                arraylist_clear (buffers);
+                for (i = 0; i < num_buffers; i++)
+                {
+                    ptr_buffer = gui_buffer_search_by_full_name (list_buffers[i]);
+                    if (gui_chat_buffer_valid (ptr_buffer,
+                                               line->data->buffer->type))
+                    {
+                        arraylist_add (buffers, ptr_buffer);
+                    }
+                }
+                string_free_split (list_buffers);
+            }
         }
         else
         {
+            arraylist_clear (buffers);
             line->data->buffer = NULL;
             return;
         }
@@ -1604,19 +1746,37 @@ gui_line_hook_update (struct t_gui_line *line,
         {
             if (ptr_value2[0])
             {
-                if ((ptr_value2[0] == '0') && (ptr_value2[1] == 'x'))
+                list_buffers = string_split (
+                    ptr_value2, ",", NULL,
+                    WEECHAT_STRING_SPLIT_STRIP_LEFT
+                    | WEECHAT_STRING_SPLIT_STRIP_RIGHT
+                    | WEECHAT_STRING_SPLIT_COLLAPSE_SEPS,
+                    0, &num_buffers);
+                if (list_buffers)
                 {
-                    rc = sscanf (ptr_value2 + 2, "%lx", &value_pointer);
-                    ptr_buffer = (struct t_gui_buffer *)value_pointer;
-                    if ((rc != EOF) && (rc >= 1)
-                        && gui_chat_buffer_valid (ptr_buffer, line->data->buffer->type))
+                    arraylist_clear (buffers);
+                    for (i = 0; i < num_buffers; i++)
                     {
-                        line->data->buffer = ptr_buffer;
+                        if ((list_buffers[i][0] == '0')
+                            && (list_buffers[i][1] == 'x'))
+                        {
+                            rc = sscanf (list_buffers[i] + 2,
+                                         "%lx", &value_pointer);
+                            ptr_buffer = (struct t_gui_buffer *)value_pointer;
+                            if ((rc != EOF) && (rc >= 1)
+                                && gui_chat_buffer_valid (
+                                    ptr_buffer, line->data->buffer->type))
+                            {
+                                arraylist_add (buffers, ptr_buffer);
+                            }
+                        }
                     }
+                    string_free_split (list_buffers);
                 }
             }
             else
             {
+                arraylist_clear (buffers);
                 line->data->buffer = NULL;
                 return;
             }
diff --git a/src/gui/gui-line.h b/src/gui/gui-line.h
index ba4d7fdee..8dd5daf2f 100644
--- a/src/gui/gui-line.h
+++ b/src/gui/gui-line.h
@@ -128,7 +128,10 @@ extern struct t_gui_line *gui_line_new (struct t_gui_buffer *buffer,
                                         const char *tags,
                                         const char *prefix,
                                         const char *message);
+extern struct t_gui_line *gui_line_dup_for_buffer (struct t_gui_line *line,
+                                                   struct t_gui_buffer *buffer);
 extern void gui_line_hook_update (struct t_gui_line *line,
+                                  struct t_arraylist *buffers,
                                   struct t_hashtable *hashtable,
                                   struct t_hashtable *hashtable2);
 extern void gui_line_add (struct t_gui_line *line);
diff --git a/tests/unit/gui/test-gui-line.cpp b/tests/unit/gui/test-gui-line.cpp
index 4312cf87e..f6cca788a 100644
--- a/tests/unit/gui/test-gui-line.cpp
+++ b/tests/unit/gui/test-gui-line.cpp
@@ -32,6 +32,9 @@ extern "C"
 #include "src/gui/gui-filter.h"
 #include "src/gui/gui-hotlist.h"
 #include "src/gui/gui-line.h"
+
+extern void gui_line_tags_dup (struct t_gui_line_data *line_data,
+                               struct t_gui_line_data *line_data2);
 }
 
 #define WEE_BUILD_STR_PREFIX_MSG(__result, __prefix, __message)         \
@@ -99,12 +102,13 @@ TEST(GuiLine, LinesAlloc)
 /*
  * Tests functions:
  *   gui_line_tags_alloc
+ *   gui_line_tags_dup
  *   gui_line_tags_free
  */
 
 TEST(GuiLine, TagsAlloc)
 {
-    struct t_gui_line_data line_data;
+    struct t_gui_line_data line_data, line_data2;
 
     memset (&line_data, 0, sizeof (line_data));
 
@@ -152,6 +156,42 @@ TEST(GuiLine, TagsAlloc)
     LONGS_EQUAL(3, line_data.tags_count);
     gui_line_tags_free (&line_data);
 
+    line_data.tags_array = NULL;
+    line_data.tags_count = 0;
+    line_data2.tags_array = (char **)0x1;
+    line_data2.tags_count = 1;
+    gui_line_tags_dup (&line_data, &line_data2);
+    POINTERS_EQUAL(NULL, line_data2.tags_array);
+    LONGS_EQUAL(0, line_data2.tags_count);
+
+    line_data.tags_array = NULL;
+    line_data.tags_count = 0;
+    line_data2.tags_array = (char **)0x1;
+    line_data2.tags_count = 0;
+    gui_line_tags_alloc (&line_data, "tag1");
+    gui_line_tags_dup (&line_data, &line_data2);
+    CHECK(line_data2.tags_array);
+    STRCMP_EQUAL("tag1", line_data2.tags_array[0]);
+    POINTERS_EQUAL(NULL, line_data2.tags_array[1]);
+    LONGS_EQUAL(1, line_data2.tags_count);
+    gui_line_tags_free (&line_data);
+    gui_line_tags_free (&line_data2);
+
+    line_data.tags_array = NULL;
+    line_data.tags_count = 0;
+    line_data2.tags_array = (char **)0x1;
+    line_data2.tags_count = 0;
+    gui_line_tags_alloc (&line_data, "tag1,tag2,tag3");
+    gui_line_tags_dup (&line_data, &line_data2);
+    CHECK(line_data2.tags_array);
+    STRCMP_EQUAL("tag1", line_data2.tags_array[0]);
+    STRCMP_EQUAL("tag2", line_data2.tags_array[1]);
+    STRCMP_EQUAL("tag3", line_data2.tags_array[2]);
+    POINTERS_EQUAL(NULL, line_data2.tags_array[3]);
+    LONGS_EQUAL(3, line_data2.tags_count);
+    gui_line_tags_free (&line_data);
+    gui_line_tags_free (&line_data2);
+
     gui_line_tags_free (NULL);
 }
 
@@ -984,6 +1024,101 @@ TEST(GuiLine, New)
     free (str_time);
 }
 
+/*
+ * Tests functions:
+ *   gui_line_dup_for_buffer
+ */
+
+TEST(GuiLine, DupForBuffer)
+{
+    struct t_gui_buffer *buffer, *buffer2;
+    struct t_gui_line *line1, *line2;
+    time_t date_printed, date;
+    char *str_time;
+
+    date_printed = time (NULL);
+    date = date_printed - 1;
+    str_time = gui_chat_get_time_string (date);
+
+    POINTERS_EQUAL(NULL, gui_line_dup_for_buffer (NULL, NULL));
+
+    /* create two new test buffers (formatted content) */
+    buffer = gui_buffer_new_user ("test", GUI_BUFFER_TYPE_FORMATTED);
+    CHECK(buffer);
+    buffer2 = gui_buffer_new_user ("test2", GUI_BUFFER_TYPE_FORMATTED);
+    CHECK(buffer2);
+
+    line1 = gui_line_new (buffer, 0, date, date_printed, "tag1,tag2,tag3",
+                          "prefix", "message");
+    CHECK(line1);
+    CHECK(line1->data);
+    line2 = gui_line_dup_for_buffer (line1, buffer2);
+    CHECK(line2);
+    CHECK(line2->data);
+    POINTERS_EQUAL(NULL, line2->prev_line);
+    POINTERS_EQUAL(NULL, line2->next_line);
+    POINTERS_EQUAL(buffer2, line2->data->buffer);
+    LONGS_EQUAL(0, line2->data->id);
+    LONGS_EQUAL(-1, line2->data->y);
+    LONGS_EQUAL(date, line2->data->date);
+    LONGS_EQUAL(date_printed, line2->data->date_printed);
+    STRCMP_EQUAL(str_time, line2->data->str_time);
+    LONGS_EQUAL(3, line2->data->tags_count);
+    CHECK(line2->data->tags_array);
+    STRCMP_EQUAL("tag1", line2->data->tags_array[0]);
+    STRCMP_EQUAL("tag2", line2->data->tags_array[1]);
+    STRCMP_EQUAL("tag3", line2->data->tags_array[2]);
+    LONGS_EQUAL(1, line2->data->displayed);
+    LONGS_EQUAL(GUI_HOTLIST_LOW, line2->data->notify_level);
+    LONGS_EQUAL(0, line2->data->highlight);
+    LONGS_EQUAL(0, line2->data->refresh_needed);
+    STRCMP_EQUAL("prefix", line2->data->prefix);
+    LONGS_EQUAL(6, line2->data->prefix_length);
+    STRCMP_EQUAL("message", line2->data->message);
+
+    gui_buffer_close (buffer);
+    gui_buffer_close (buffer2);
+
+    /* create two new test buffers (free content) */
+    buffer = gui_buffer_new_user ("test", GUI_BUFFER_TYPE_FREE);
+    CHECK(buffer);
+    buffer2 = gui_buffer_new_user ("test2", GUI_BUFFER_TYPE_FREE);
+    CHECK(buffer);
+
+    line1 = gui_line_new (buffer, 3, date, date_printed, "tag1,tag2,tag3",
+                          NULL, "message");
+    CHECK(line1);
+    CHECK(line1->data);
+    line2 = gui_line_dup_for_buffer (line1, buffer2);
+    CHECK(line1);
+    CHECK(line1->data);
+    POINTERS_EQUAL(NULL, line2->prev_line);
+    POINTERS_EQUAL(NULL, line2->next_line);
+    POINTERS_EQUAL(buffer2, line2->data->buffer);
+    LONGS_EQUAL(3, line2->data->id);
+    LONGS_EQUAL(3, line2->data->y);
+    LONGS_EQUAL(date, line2->data->date);
+    LONGS_EQUAL(date_printed, line2->data->date_printed);
+    POINTERS_EQUAL(NULL, line2->data->str_time);
+    LONGS_EQUAL(3, line2->data->tags_count);
+    CHECK(line2->data->tags_array);
+    STRCMP_EQUAL("tag1", line2->data->tags_array[0]);
+    STRCMP_EQUAL("tag2", line2->data->tags_array[1]);
+    STRCMP_EQUAL("tag3", line2->data->tags_array[2]);
+    LONGS_EQUAL(1, line2->data->displayed);
+    LONGS_EQUAL(GUI_HOTLIST_LOW, line2->data->notify_level);
+    LONGS_EQUAL(0, line2->data->highlight);
+    LONGS_EQUAL(1, line2->data->refresh_needed);
+    POINTERS_EQUAL(NULL, line2->data->prefix);
+    LONGS_EQUAL(0, line2->data->prefix_length);
+    STRCMP_EQUAL("message", line2->data->message);
+
+    gui_buffer_close (buffer);
+    gui_buffer_close (buffer2);
+
+    free (str_time);
+}
+
 /*
  * Tests functions:
  *   gui_line_hook_update