Adopt to new open/save dialog API.

src/app/atom.coffee

@@ -171,8 +171,9 @@ window.atom =
     callbacks[chosen]?()
 
   showSaveDialog: (callback) ->
-    @presentModal =>
-      @sendMessageToBrowserProcess('showSaveDialog', [], (path) => @dismissModal(callback, path))
+    currentWindow = remote.getCurrentWindow()
+    result = remote.require('dialog').showSaveDialog currentWindow, title: 'Save File', defaultPath: path
+    callback(result)
 
   presentModal: (fn) ->
     if @presentingModal

src/main.coffee

@@ -122,9 +122,8 @@ class AtomApplication
 
     ipc.on 'open-folder', =>
       currentWindow = BrowserWindow.getFocusedWindow()
-      dialog.openFolder currentWindow, {}, (result, paths...) =>
-        console.log paths
-        @createAtomWindow(path) for path in paths
+      paths = dialog.showOpenDialog title: 'Open', properties: ['openFile', 'openDirectory', 'multiSelections', 'createDirectory']
+      @createAtomWindow(path) for path in paths if paths?
 
     ipc.on 'new-window', =>
       @createAtomWindow()