Style color of folded line numbers

src/app/edit-session.coffee

@@ -307,6 +307,10 @@ class EditSession
     fold.destroy()
     @setCursorBufferPosition([fold.startRow, 0])
 
+  isFoldedAtBufferRow: (bufferRow) ->
+    screenRow = @screenPositionForBufferPosition([bufferRow]).row
+    @isFoldedAtScreenRow(screenRow)
+
   isFoldedAtScreenRow: (screenRow) ->
     @lineForScreenRow(screenRow)?.fold?
 

src/app/editor.coffee

@@ -276,6 +276,7 @@ class Editor extends View
   destroyFold: (foldId) -> @activeEditSession.destroyFold(foldId)
   destroyFoldsContainingBufferRow: (bufferRow) -> @activeEditSession.destroyFoldsContainingBufferRow(bufferRow)
   isFoldedAtScreenRow: (screenRow) -> @activeEditSession.isFoldedAtScreenRow(screenRow)
+  isFoldedAtBufferRow: (bufferRow) -> @activeEditSession.isFoldedAtBufferRow(bufferRow)
 
   lineForScreenRow: (screenRow) -> @activeEditSession.lineForScreenRow(screenRow)
   linesForScreenRows: (start, end) -> @activeEditSession.linesForScreenRows(start, end)

src/app/gutter.coffee

@@ -58,16 +58,19 @@ class Gutter extends View
     @renderLineNumbers(renderFrom, renderTo) if performUpdate
 
   renderLineNumbers: (startScreenRow, endScreenRow) ->
-    rows = @editor().bufferRowsForScreenRows(startScreenRow, endScreenRow)
+    editor = @editor()
+    rows = editor.bufferRowsForScreenRows(startScreenRow, endScreenRow)
 
-    cursorScreenRow = @editor().getCursorScreenPosition().row
+    cursorScreenRow = editor.getCursorScreenPosition().row
     @lineNumbers[0].innerHTML = $$$ ->
       for row in rows
         if row == lastScreenRow
           rowValue = '•'
         else
           rowValue = row + 1
-        @div {class: 'line-number'}, rowValue
+        classes = ['line-number']
+        classes.push('fold') if editor.isFoldedAtBufferRow(row)
+        @div rowValue, class: classes.join(' ')
         lastScreenRow = row
 
     @calculateWidth()