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src/components/structures/MessagePanel.js

@@ -450,6 +450,11 @@ module.exports = React.createClass({
         if (prevEvent !== null
                 && prevEvent.sender && mxEv.sender
                 && mxEv.sender.userId === prevEvent.sender.userId
+                // The preferred way of checking for 'continuation messages' is by
+                // checking whether subsiquent messages from the same user have a
+                // message body. This is because all messages intended to be displayed
+                // should have a 'body' whereas some (non-m.room) messages (such as
+                // m.sticker) may not have a message 'type'.
                 && Boolean(mxEv.getContent().body) == Boolean(prevEvent.getContent().body)) {
             continuation = true;
         }