Display a 'Set Topic' button if there is no topic or it's a 0-len string.

webclient/app.css

@@ -280,7 +280,6 @@ a:active  { color: #000; }
     color: #888;
     font-size: 12px;
     padding-right: 5px;
-    float: right;
     width: 15em;
     overflow: hidden;
     white-space: nowrap;
@@ -301,6 +300,15 @@ a:active  { color: #000; }
     width: 100%;
 }
 
+.roomTopicSection {
+    float: right;
+    width: 100%;
+}
+
+.roomTopicSetNew {
+    float: right;
+}
+
 .roomHeaderInfo {
     float: right;
     margin-top: 15px;

webclient/room/room-controller.js

@@ -51,7 +51,14 @@ angular.module('RoomController', ['ngSanitize', 'matrixFilter', 'mFileInput'])
                 console.log("Warning: Already editing topic.");
                 return;
             }
-            $scope.topic.newTopicText = $rootScope.events.rooms[$scope.room_id]['m.room.topic'].content.topic;
+            var topicEvent = $rootScope.events.rooms[$scope.room_id]['m.room.topic'];
+            if (topicEvent) {
+                $scope.topic.newTopicText = topicEvent.content.topic;
+            }
+            else {
+                $scope.topic.newTopicText = "";
+            }
+            
             $scope.topic.isEditing = true;
         },
         updateTopic: function() {

webclient/room/room.html

@@ -6,16 +6,20 @@
             <div id="roomName">
                 {{ room_id  | mRoomName }}
             </div>
-            <div id="roomTopic" ng-show="events.rooms[room_id]['m.room.topic'].content.topic">
-                <div ng-hide="topic.isEditing" ng-dblclick="topic.editTopic()">
+            <div class="roomTopicSection">
+                <button ng-hide="events.rooms[room_id]['m.room.topic'].content.topic || topic.isEditing"
+                    ng-click="topic.editTopic()" class="roomTopicSetNew">
+                    Set Topic
+                </button>
+                <div ng-show="events.rooms[room_id]['m.room.topic'].content.topic || topic.isEditing">
+                    <div ng-hide="topic.isEditing" ng-dblclick="topic.editTopic()" id="roomTopic">
                         {{ events.rooms[room_id]['m.room.topic'].content.topic | limitTo: 200}}
                     </div>
-                
                     <form ng-submit="topic.updateTopic()" ng-show="topic.isEditing" class="roomTopicForm">
                         <input ng-model="topic.newTopicText" ng-blur="topic.cancelEdit()" class="roomTopicInput" 
                         autofocus />
                     </form>
-                
+                </div>
             </div>
         </div>
     </div>