diff --git a/plugins/project/project.coffee b/plugins/project/project.coffee
index 15fdbc2fd..6d26fdac5 100644
--- a/plugins/project/project.coffee
+++ b/plugins/project/project.coffee
@@ -1,7 +1,8 @@
 $ = require 'jquery'
 _ = require 'underscore'
 
-{Chrome, Dir, File, Process} = require 'osx'
+{Chrome, Process} = require 'osx'
+File = require 'fs'
 
 Editor  = require 'editor'
 bindKey = Editor.bindKey
@@ -40,10 +41,10 @@ exports.reload = ->
 
   $('#project li').remove()
 
-  files = Dir.list dir
+  files = File.list dir
   listItems = _.map files, (path) ->
     filename = path.replace(dir, "").substring 1
-    type = if Dir.isDir(path) then 'dir' else 'file'
+    type = if File.isDir(path) then 'dir' else 'file'
     "<li class='#{type}' path='#{encodeURIComponent path}'>#{filename}</li>"
 
   $('#project .files').append listItems.join '\n'
diff --git a/plugins/tabs/tabs.coffee b/plugins/tabs/tabs.coffee
index 1e903b09a..f9d036fad 100644
--- a/plugins/tabs/tabs.coffee
+++ b/plugins/tabs/tabs.coffee
@@ -1,7 +1,8 @@
 $ = require 'jquery'
 _ = require 'underscore'
 
-{Chrome, File, Dir, Process} = require 'osx'
+{Chrome, Process} = require 'osx'
+File = require 'fs'
 {bindKey} = require 'editor'
 
 
diff --git a/src/editor.coffee b/src/editor.coffee
index a064499cc..acf445971 100644
--- a/src/editor.coffee
+++ b/src/editor.coffee
@@ -3,7 +3,7 @@
 $ = require 'jquery'
 _ = require 'underscore'
 
-{Chrome, Process, Dir} = require 'osx'
+{Chrome, Process} = require 'osx'
 File = require 'fs'
 
 ace = require 'ace/ace'
@@ -24,7 +24,7 @@ save = ->
 exports.open = open = (path) ->
   filename = path
 
-  if Dir.isDir filename
+  if File.isDir filename
     Process.cwd filename
     Chrome.title _.last filename.split '/'
     editor.getSession().setValue ""
diff --git a/src/fs.coffee b/src/fs.coffee
index 78e1214e6..60fa2e426 100644
--- a/src/fs.coffee
+++ b/src/fs.coffee
@@ -12,6 +12,14 @@ module.exports =
     else
       path
 
+  # Returns true if the file specified by path exists and is a
+  # directory.
+  isDirectory: (path) ->
+    isDir = new jscocoa.outArgument
+    exists = OSX.NSFileManager.defaultManager.
+      fileExistsAtPath_isDirectory path, isDir
+    exists and isDir.valueOf()
+
   # Returns true if the file specified by path exists and is a
   # regular file.
   isFile: (path) ->
@@ -20,6 +28,24 @@ module.exports =
       fileExistsAtPath_isDirectory path, isDir
     exists and not isDir.valueOf()
 
+  # Returns an array with all the names of files contained
+  # in the directory path.
+  list: (path, recursive) ->
+    path = File.absolute path
+    fm = OSX.NSFileManager.defaultManager
+    if recursive
+      paths = fm.subpathsAtPath path
+    else
+      paths = fm.contentsOfDirectoryAtPath_error path, null
+    _.map paths, (entry) -> "#{path}/#{entry}"
+
+  # Return an array with all directories below (and including)
+  # the given path, as discovered by depth-first traversal. Entries
+  # are in lexically sorted order within directories. Symbolic links
+  # to directories are not traversed into.
+  listDirectoryTree: (path) ->
+    @list path, true
+
   # Open, read, and close a file, returning the file's contents.
   read: (path) ->
     OSX.NSString.stringWithContentsOfFile(@absolute path).toString()
diff --git a/src/osx.coffee b/src/osx.coffee
index bc401d22f..92785a89b 100644
--- a/src/osx.coffee
+++ b/src/osx.coffee
@@ -87,22 +87,6 @@ Chrome =
   appRoot: ->
     OSX.NSBundle.mainBundle.resourcePath
 
-# Handles the file system
-Dir =
-  list: (path, recursive) ->
-    path = File.absolute path
-    fm = OSX.NSFileManager.defaultManager
-    if recursive
-      paths = fm.subpathsAtPath path
-    else
-      paths = fm.contentsOfDirectoryAtPath_error path, null
-    _.map paths, (entry) -> "#{path}/#{entry}"
-  isDir: (path) ->
-    isDir = new jscocoa.outArgument
-    exists = OSX.NSFileManager.defaultManager.
-      fileExistsAtPath_isDirectory path, isDir
-    exists and isDir.valueOf()
-
 Process =
   cwd: (path) ->
     if path?
diff --git a/src/plugins.coffee b/src/plugins.coffee
index abe2261d0..4942c8cba 100644
--- a/src/plugins.coffee
+++ b/src/plugins.coffee
@@ -1,10 +1,10 @@
 $ = require 'jquery'
 _ = require 'underscore'
 
-{Chrome, Dir} = require 'osx'
+{Chrome} = require 'osx'
 File = require 'fs'
 
-_.map Dir.list(Chrome.appRoot() + "/plugins"), (plugin) ->
+_.map File.list(Chrome.appRoot() + "/plugins"), (plugin) ->
   require plugin
 
 if css = File.read "~/.atomicity/twilight.css"
@@ -15,5 +15,5 @@ if css = File.read "~/.atomicity/twilight.css"
   style.appendChild rules
   head.appendChild style
 
-_.map Dir.list("~/.atomicity/"), (path) ->
+_.map File.list("~/.atomicity/"), (path) ->
   require path