Merge pull request #1272 from vector-im/read_marker

RoomViewController:  The unread messages label is displayed whereas t…

Riot/ViewController/RoomViewController.m

@@ -743,6 +743,8 @@
     
     if (self.roomDataSource)
     {
+        self.eventsAcknowledgementEnabled = YES;
+        
         // Set room title view
         [self refreshRoomTitle];
         
@@ -1465,6 +1467,8 @@
     
     if (previewData)
     {
+        self.eventsAcknowledgementEnabled = NO;
+        
         [self addMatrixSession:previewData.mxSession];
         
         roomPreviewData = previewData;
@@ -3002,7 +3006,7 @@
         {
             // Show "scroll to bottom" icon when the most recent message is not visible,
             // or when the timelime is not live (this icon is used to go back to live).
-            if (!self.roomDataSource.isLive || [self isBubblesTableScrollViewAtTheBottom] == NO)
+            if (!self.roomDataSource.isLive || (!self.bubblesTableView.isHidden && [self isBubblesTableScrollViewAtTheBottom] == NO))
             {
                 // Retrieve the unread messages count
                 NSUInteger unreadCount = self.roomDataSource.room.summary.localUnreadEventCount;
@@ -3554,8 +3558,8 @@
     {
         self.jumpToLastUnreadBannerContainer.hidden = YES;
         
-        // Initialize the read marker if it does not exist yet
-        if (!self.roomDataSource.room.accountData.readMarkerEventId)
+        // Initialize the read marker if it does not exist yet, except for the room preview.
+        if (!self.roomDataSource.room.accountData.readMarkerEventId && !self.isRoomPreview)
         {
             // Move the read marker to the current read receipt position by default.
             [self.roomDataSource.room forgetReadMarker];