Display heading on boundary between historical and non-historical.

(imported from commit b1669725d5a10ae086d04d0aa03341bcb0b8b858)

zephyr/static/js/message_list.js

@@ -271,7 +271,8 @@ MessageList.prototype = {
         $.each(messages, function (index, message) {
             message.include_recipient = false;
             message.include_bookend   = false;
-            if (util.same_recipient(prev, message) && self.collapse_messages) {
+            if (util.same_recipient(prev, message) && self.collapse_messages &&
+               prev.historical === message.historical) {
                 current_group.push(message.id);
             } else {
                 if (current_group.length > 0)
@@ -281,6 +282,15 @@ MessageList.prototype = {
                 // Add a space to the table, but not for the first element.
                 message.include_recipient = true;
                 message.include_bookend   = (prev !== undefined);
+                message.subscribed = false;
+                message.unsubscribed = false;
+                if (message.include_bookend && message.historical !== prev.historical) {
+                    if (message.historical) {
+                        message.unsubscribed = message.display_recipient;
+                    } else {
+                        message.subscribed = message.display_recipient;
+                    }
+                }
             }
 
             message.include_sender = true;

zephyr/static/js/zephyr.js

@@ -505,6 +505,8 @@ function add_message_metadata(message, dummy) {
     var involved_people;
 
     message.flags = message.flags || [];
+    message.historical = (message.flags !== undefined &&
+                          message.flags.indexOf('historical') !== -1);
     message.starred = message.flags.indexOf("starred") !== -1;
 
     switch (message.type) {

zephyr/static/styles/zephyr.css

@@ -392,6 +392,10 @@ td.pointer {
     font-size: 80%;
 }
 
+.tiny {
+    font-size: 20%;
+}
+
 .actions_hovered .message_time {
     color:           #0088CC;
     text-decoration: underline;

zephyr/static/templates/message.handlebars

@@ -15,7 +15,16 @@
 {{#each messages}}
 {{#with this}}
 {{#include_bookend}}
-<tr class="bookend_tr"><td /><td /><td class="bookend" /></tr>
+<tr class="bookend_tr"><td/>
+<td /><td class="bookend">
+{{#if subscribed}}
+<center>--- Subscribed to stream {{subscribed}} ---</center>
+{{/if}}
+{{#if unsubscribed}}
+<center>--- Unsubscribed from stream {{unsubscribed}} ---</center>
+{{/if}}
+<span class="tiny"><p></p></span></td>
+</tr>
 {{/include_bookend}}
 
 {{#include_recipient}}