diff --git a/services/web/public/coffee/ide/editor/Document.coffee b/services/web/public/coffee/ide/editor/Document.coffee
index 78431b8b6b..005d722a56 100644
--- a/services/web/public/coffee/ide/editor/Document.coffee
+++ b/services/web/public/coffee/ide/editor/Document.coffee
@@ -265,10 +265,10 @@ define [
 				@ide.pushEvent "externalUpdate",
 					doc_id: @doc_id
 				@trigger "externalUpdate", update
-			@doc.on "remoteop", () => 
+			@doc.on "remoteop", (args...) => 
 				@ide.pushEvent "remoteop",
 					doc_id: @doc_id
-				@trigger "remoteop"
+				@trigger "remoteop", args...
 			@doc.on "op:sent", (op) =>
 				@ide.pushEvent "op:sent",
 					doc_id: @doc_id
diff --git a/services/web/public/coffee/ide/editor/ShareJsDoc.coffee b/services/web/public/coffee/ide/editor/ShareJsDoc.coffee
index 27d325676c..4f9960f9a0 100644
--- a/services/web/public/coffee/ide/editor/ShareJsDoc.coffee
+++ b/services/web/public/coffee/ide/editor/ShareJsDoc.coffee
@@ -47,11 +47,11 @@ define [
 				@trigger "change"
 			@_doc.on "acknowledge", () =>
 				@trigger "acknowledge"
-			@_doc.on "remoteop", () =>
+			@_doc.on "remoteop", (args...) =>
 				# As soon as we're working with a collaborator, start sending
 				# ops as quickly as possible for low latency.
 				@_doc.setFlushDelay(0)
-				@trigger "remoteop"
+				@trigger "remoteop", args...
 			@_doc.on "error", (e) =>
 				@_handleError(e)
 
diff --git a/services/web/public/coffee/ide/editor/directives/aceEditor.coffee b/services/web/public/coffee/ide/editor/directives/aceEditor.coffee
index 4a697f39f9..bc4e656a1c 100644
--- a/services/web/public/coffee/ide/editor/directives/aceEditor.coffee
+++ b/services/web/public/coffee/ide/editor/directives/aceEditor.coffee
@@ -235,8 +235,9 @@ define [
 					doc = session.getDocument()
 					doc.on "change", onChange
 
-					sharejs_doc.on "remoteop.recordForUndo", () =>
+					sharejs_doc.on "remoteop.recordRemote", (op, oldSnapshot, msg) ->
 						undoManager.nextUpdateIsRemote = true
+						trackChangesManager.nextUpdateMetaData = msg?.meta
 
 					editor.initing = true
 					sharejs_doc.attachToAce(editor)
@@ -255,7 +256,7 @@ define [
 
 				detachFromAce = (sharejs_doc) ->
 					sharejs_doc.detachFromAce()
-					sharejs_doc.off "remoteop.recordForUndo"
+					sharejs_doc.off "remoteop.recordRemote"
 
 					session = editor.getSession()
 					session.off "changeScrollTop"
diff --git a/services/web/public/coffee/ide/editor/directives/aceEditor/track-changes/TrackChangesManager.coffee b/services/web/public/coffee/ide/editor/directives/aceEditor/track-changes/TrackChangesManager.coffee
index 47026eeb04..abcb8817c1 100644
--- a/services/web/public/coffee/ide/editor/directives/aceEditor/track-changes/TrackChangesManager.coffee
+++ b/services/web/public/coffee/ide/editor/directives/aceEditor/track-changes/TrackChangesManager.coffee
@@ -23,10 +23,24 @@ define [
 
 			onChange = (e) =>
 				if !@editor.initing and @enabled
-					@applyChange(e)
+					# This change is trigger by a sharejs 'change' event, which is before the
+					# sharejs 'remoteop' event. So wait until the next event loop when the 'remoteop'
+					# will have fired, before we decide if it was a remote op.
 					setTimeout () =>
-						@checkMapping()
-					, 100
+						if @nextUpdateMetaData?
+							# The remote op may have contained multiple atomic ops, each of which is an Ace
+							# 'change' event (i.e. bulk commenting out of lines is a single remote op
+							# but gives us one event for each % inserted). These all come in a single event loop
+							# though, so wait until the next one before clearing the metadata.
+							setTimeout () =>
+								@nextUpdateMetaData = null
+
+						@applyChange(e)
+						
+						# TODO: Just for debugging, remove before going live.
+						setTimeout () =>
+							@checkMapping()
+						, 100
 
 			@editor.on "changeSession", (e) =>
 				e.oldSession?.getDocument().off "change", onChange
@@ -176,6 +190,7 @@ define [
 				marker = markers[marker_id]
 				marker.range.start = start
 				marker.range.end = end
+			@editor.renderer.updateBackMarkers()
 			@updateReviewEntriesScope()
 	
 	class ChangesTracker extends EventEmitter
diff --git a/services/web/public/coffee/ide/editor/sharejs/vendor/client/doc.coffee b/services/web/public/coffee/ide/editor/sharejs/vendor/client/doc.coffee
index dd4f26ceb0..d25baf89d5 100644
--- a/services/web/public/coffee/ide/editor/sharejs/vendor/client/doc.coffee
+++ b/services/web/public/coffee/ide/editor/sharejs/vendor/client/doc.coffee
@@ -64,7 +64,7 @@ class Doc
       server_ = @type.transform server, client, 'right'
       return [client_, server_]
   
-  _otApply: (docOp, isRemote) ->
+  _otApply: (docOp, isRemote, msg) ->
     oldSnapshot = @snapshot
     @snapshot = @type.apply(@snapshot, docOp)
 
@@ -72,7 +72,7 @@ class Doc
     # The reason is that the OT type APIs might need to access the snapshots to
     # determine information about the received op.
     @emit 'change', docOp, oldSnapshot
-    @emit 'remoteop', docOp, oldSnapshot if isRemote
+    @emit 'remoteop', docOp, oldSnapshot, msg if isRemote
   
   _connectionStateChanged: (state, data) ->
     switch state
@@ -185,7 +185,7 @@ class Doc
           # functionality, because its really a local op. Basically, the problem is that
           # if the client's op is rejected by the server, the editor window should update
           # to reflect the undo.
-          @_otApply undo, true
+          @_otApply undo, true, msg
         else
           @emit 'error', "Op apply failed (#{error}) and the op could not be reverted"
 
@@ -234,7 +234,7 @@ class Doc
         
       @version++
       # Finally, apply the op to @snapshot and trigger any event listeners
-      @_otApply docOp, true
+      @_otApply docOp, true, msg
 
     else if msg.meta
       {path, value} = msg.meta