Create a placeholder for each image of the chat thread. The height of this placeholder is the height of the image so that the scroller position will not be disrupted when the image will be actually loaded and displayed in its full height

webclient/room/room.html

@@ -41,7 +41,10 @@
                     <div class="bubble">
                         <span ng-hide='msg.content.msgtype !== "m.emote"' ng-bind-html="'* ' + (members[msg.user_id].displayname || msg.user_id) + ' ' + msg.content.body | linky:'_blank'"/>
                         <span ng-hide='msg.content.msgtype !== "m.text"' ng-bind-html="((msg.content.msgtype === 'm.text') ? msg.content.body : '') | linky:'_blank'"/>
-                        <img class="image" ng-hide='msg.content.msgtype !== "m.image"' ng-src="{{ msg.content.url }}"/>
+                        <div ng-hide='msg.content.msgtype !== "m.image"'
+                             ng-style="{ 'height' : (msg.content.body.h < 320) ? msg.content.body.h : 320}">
+                            <img class="image" ng-src="{{ msg.content.url }}"/>
+                        </div>
                     </div>
                 </td>
                 <td class="rightBlock">