More on read receipts: listen for events, add keys & class / very minimal css.

src/skins/vector/css/molecules/EventTile.css

@@ -123,3 +123,12 @@ limitations under the License.
 .mx_EventTile.menu .mx_MessageTimestamp {
     visibility: visible;
 }
+
+.mx_EventTile_readAvatars {
+    float: right;
+}
+
+.mx_EventTile_readAvatars .mx_MemberAvatar {
+    margin-left: 1px;
+    margin-right: 1px;
+}

src/skins/vector/views/molecules/EventTile.js

@@ -85,11 +85,11 @@ module.exports = React.createClass({
         for (var i = 0; i < userIds.length; ++i) {
             var member = room.getMember(userIds[i]);
             avatars.push(
-                <MemberAvatar member={member} width={14} height={14} resizeMethod="crop" />
+                <MemberAvatar key={member.userId} member={member} width={14} height={14} resizeMethod="crop" />
             );
         }
 
-        return <span>{ avatars }</span>;
+        return <span className="mx_EventTile_readAvatars">{ avatars }</span>;
     },
 
     render: function() {