[FIX] fix error channel_seen function in base.js

[FIX] fix error inline method in base.js
[ADD] add css file for make grey color for link and display recipients when overmouse
[IMP] add "To:" before recipients and make link on recipient name
[DOC] add info about old messages in index.rst

mail_base/static/src/js/base.js

@@ -845,7 +845,7 @@ chat_manager.undo_mark_as_read = function (message_ids, channel) {
 chat_manager.mark_channel_as_seen = function (channel) {
         if (channel.unread_counter > 0 && channel.type !== 'static') {
             chat_manager.mail_tools.update_channel_unread_counter(channel, 0);
-            chat_manager.mail_tools.channel_seen(channel);
+            channel_seen(channel);
         }
     };
 chat_manager.get_channels = function () {
@@ -1043,7 +1043,7 @@ chat_manager.get_channels_preview = function (channels) {
         });
     };
 chat_manager.get_message_body_preview = function (message_body) {
-        return chat_manager.mail_tools.parse_and_transform(message_body, inline);
+        return chat_manager.mail_tools.parse_and_transform(message_body, chat_manager.mail_tools.inline);
     };
 chat_manager.search_partner = function (search_val, limit) {
         return PartnerModel.call('im_search', [search_val, limit || 20], {}, {shadow: true}).then(function(result) {

mail_to/doc/index.rst

@@ -6,4 +6,5 @@ Usage
 =====
 
 * Open Discuss menu
-* All messages have Recipients info
+* All messages have Recipients info
+* For messages created before install module it not will work where the recipients is not set

mail_to/static/src/css/mail_to.css

@@ -0,0 +1,9 @@
+.grey {
+    color: grey;
+}
+.o_mail_thread .o_thread_message span.recipients_info {
+    opacity: 0;
+}
+.o_mail_thread .o_thread_message:hover span.recipients_info {
+    opacity: 1;
+}

mail_to/static/src/xml/recipient.xml

@@ -1,10 +1,16 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <template>
     <t t-extend="mail.ChatThread.Message">
-        <t t-jquery="p[class=o_mail_info]>span" t-operation="before">
+        <t t-jquery="p[class=o_mail_info]>span" t-operation="after">
             <span class="recipients_info">
+                <t t-if="message.partner_ids.length > 0">To: </t>
                 <t t-foreach="message.partner_ids" t-as="p">
-                    <i t-att-data-message-id="message.id" title="Recipients Info" t-esc="p[1]"/>
+                    <a t-att-href="_.str.sprintf('/web?#id=%s&amp;view_type=form&amp;model=res.partner', p[0])"
+                       t-att-data-oe-model="message.model"
+                       t-att-data-oe-id="message.res_id"
+                       class="grey">
+                        <i t-att-data-message-id="message.id" title="Recipients Info" t-esc="p[1]"/>
+                    </a>
                 </t>
             </span>
         </t>

mail_to/templates.xml

@@ -5,6 +5,7 @@
                   name="mail_to_assets_backend"
                   inherit_id="web.assets_backend">
             <xpath expr="." position="inside">
+                <link rel="stylesheet" href="/mail_to/static/src/css/mail_to.css"/>
                 <script src="/mail_to/static/src/js/mail_to.js" type="text/javascript"></script>
             </xpath>
         </template>