Keep scrolling tile around for mousewheel

src/text-editor-component.coffee

@@ -354,7 +354,6 @@ class TextEditorComponent
       event.preventDefault() unless previousScrollLeft is @presenter.getScrollLeft()
     else
       # Scrolling vertically
-      @presenter.setMouseWheelScreenRow(@screenRowForNode(event.target))
       previousScrollTop = @presenter.getScrollTop()
       @presenter.setScrollTop(previousScrollTop - Math.round(wheelDeltaY * @scrollSensitivity))
       event.preventDefault() unless previousScrollTop is @presenter.getScrollTop()

src/text-editor-presenter.coffee

@@ -317,9 +317,11 @@ class TextEditorPresenter
     visibleTilesIndexes = [startIndex...endIndex]
 
     for index, tile of @state.content.tiles
-      unless index in visibleTilesIndexes
-        delete @state.content.tiles[index]
-        delete @linesPresentersByTileIndex[index]
+      continue if index is @scrollingTile
+      continue if index in visibleTilesIndexes
+
+      delete @state.content.tiles[index]
+      delete @linesPresentersByTileIndex[index]
 
     for index in visibleTilesIndexes
       presenter = @linesPresentersByTileIndex[index] ?= new LinesPresenter(@)
@@ -728,8 +730,8 @@ class TextEditorPresenter
 
   didStopScrolling: ->
     @state.content.scrollingVertically = false
-    if @mouseWheelScreenRow?
-      @mouseWheelScreenRow = null
+    if @scrollingTile?
+      @scrollingTile = null
       @shouldUpdateTilesState = true
       @shouldUpdateLineNumbersState = true
       @shouldUpdateCustomGutterDecorationState = true
@@ -895,9 +897,9 @@ class TextEditorPresenter
 
       @emitDidUpdateState()
 
-  setMouseWheelScreenRow: (mouseWheelScreenRow) ->
-    unless @mouseWheelScreenRow is mouseWheelScreenRow
-      @mouseWheelScreenRow = mouseWheelScreenRow
+  setScrollingTile: (tileId) ->
+    if @scrollingTile isnt tileId
+      @scrollingTile = tileId
       @didStartScrolling()
 
   setBaseCharacterWidth: (baseCharacterWidth) ->

src/tile-component.coffee

@@ -21,9 +21,13 @@ class TileComponent
     @screenRowsByLineId = {}
     @lineIdsByScreenRow = {}
     @domNode = document.createElement("div")
+    @domNode.addEventListener("mousewheel", @onMouseWheel)
     @domNode.style.position = "absolute"
     @domNode.classList.add("tile")
 
+  onMouseWheel: =>
+    @presenter.setScrollingTile(@id)
+
   getDomNode: ->
     @domNode