diff --git a/services/web/app/views/project/editor/review-panel.pug b/services/web/app/views/project/editor/review-panel.pug
index 72e6640cdb..93ff664eed 100644
--- a/services/web/app/views/project/editor/review-panel.pug
+++ b/services/web/app/views/project/editor/review-panel.pug
@@ -79,6 +79,7 @@
 						on-submit="submitNewComment(content);"
 						on-cancel="cancelNewComment();"
 						on-indicator-click="toggleReviewPanel();"
+						layout-to-left="reviewPanel.layoutToLeft"
 					)
 
 	.rp-entry-list(
@@ -310,7 +311,7 @@ script(type='text/ng-template', id='addCommentEntryTemplate')
 			ng-if="!commentState.adding"
 			ng-click="startNewComment(); onIndicatorClick();"
 			tooltip="Add a comment"
-			tooltip-placement="right"
+			tooltip-placement="{{ layoutToLeft ? 'left' : 'right' }}"
 			tooltip-append-to-body="true"
 		)
 			i.fa.fa-commenting
diff --git a/services/web/public/coffee/ide/review-panel/RangesTracker.coffee b/services/web/public/coffee/ide/review-panel/RangesTracker.coffee
index e31b84f051..865ecf4ef6 100644
--- a/services/web/public/coffee/ide/review-panel/RangesTracker.coffee
+++ b/services/web/public/coffee/ide/review-panel/RangesTracker.coffee
@@ -105,6 +105,7 @@ load = (EventEmitter) ->
 				throw new Error("unknown op type")
 			
 		addComment: (op, metadata) ->
+			# TODO: Don't allow overlapping comments?
 			@comments.push comment = {
 				id: op.t or @newId()
 				op: # Copy because we'll modify in place
@@ -167,12 +168,14 @@ load = (EventEmitter) ->
 			op_length = op.i.length
 			op_end = op.p + op_length
 
+
 			already_merged = false
 			previous_change = null
 			moved_changes = []
 			remove_changes = []
 			new_changes = []
-			for change in @changes
+
+			for change, i in @changes
 				change_start = change.op.p
 				
 				if change.op.d?
@@ -200,6 +203,16 @@ load = (EventEmitter) ->
 					# Only merge inserts if they are from the same user
 					is_same_user = metadata.user_id == change.metadata.user_id
 					
+					# If this is an insert op at the end of an existing insert with a delete following, and it cancels out the following
+					# delete then we shouldn't append it to this insert, but instead only cancel the following delete.
+					# E.g.
+					#                   foo|<--- about to insert 'b' here
+					#  inserted 'foo'  --^ ^-- deleted 'bar'
+					# should become just 'foo' not 'foob' (with the delete marker becoming just 'ar'), .
+					next_change = @changes[i+1]
+					is_op_adjacent_to_next_delete = next_change? and next_change.op.d? and op.p == change_end and next_change.op.p == op.p
+					will_op_cancel_next_delete = is_op_adjacent_to_next_delete and next_change.op.d.slice(0, op.i.length) == op.i
+					
 					# If there is a delete at the start of the insert, and we're inserting
 					# at the start, we SHOULDN'T merge since the delete acts as a partition.
 					# The previous op will be the delete, but it's already been shifted by this insert
@@ -222,7 +235,8 @@ load = (EventEmitter) ->
 					if @track_changes and
 							is_change_overlapping and
 							!is_insert_blocked_by_delete and
-							!already_merged and 
+							!already_merged and
+							!will_op_cancel_next_delete and
 							is_same_user
 						offset = op_start - change_start
 						change.op.i = change.op.i.slice(0, offset) + op.i + change.op.i.slice(offset)
@@ -398,8 +412,8 @@ load = (EventEmitter) ->
 		_addOp: (op, metadata) ->
 			change = {
 				id: @newId()
-				op: op
-				metadata: metadata
+				op: @_clone(op) # Don't take a reference to the existing op since we'll modify this in place with future changes
+				metadata: @_clone(metadata)
 			}
 			@changes.push change
 
@@ -471,6 +485,11 @@ load = (EventEmitter) ->
 				else # Only update to the current change if we haven't removed it.
 					previous_change = change
 			return { moved_changes, remove_changes }
+		
+		_clone: (object) ->
+			clone = {}
+			(clone[k] = v for k,v of object)
+			return clone
 
 if define?
 	define ["utils/EventEmitter"], load
diff --git a/services/web/public/coffee/ide/review-panel/directives/addCommentEntry.coffee b/services/web/public/coffee/ide/review-panel/directives/addCommentEntry.coffee
index c23c37b674..c30eaadd0f 100644
--- a/services/web/public/coffee/ide/review-panel/directives/addCommentEntry.coffee
+++ b/services/web/public/coffee/ide/review-panel/directives/addCommentEntry.coffee
@@ -9,6 +9,7 @@ define [
 			onSubmit: "&"
 			onCancel: "&"
 			onIndicatorClick: "&"
+			layoutToLeft: "="
 		link: (scope, element, attrs) ->
 			scope.state =
 				isAdding: false