diff -r 095fbf03cad7 Lib/idlelib/IOBinding.py
--- a/Lib/idlelib/IOBinding.py	Wed Apr 02 15:51:38 2014 -0400
+++ b/Lib/idlelib/IOBinding.py	Thu Apr 03 20:58:59 2014 +0530
@@ -512,10 +512,14 @@
 
     def asksavefile(self):
         dir, base = self.defaultfilename("save")
+        filetypes = self.filetypes
+        if not self.editwin.ispythonsource(self.filename):
+            #See issue21140
+            filetypes[0], filetypes[1] = filetypes[1], filetypes[0]
         if not self.savedialog:
             self.savedialog = tkFileDialog.SaveAs(
                     master=self.text,
-                    filetypes=self.filetypes,
+                    filetypes=filetypes,
                     defaultextension=self.defaultextension)
         filename = self.savedialog.show(initialdir=dir, initialfile=base)
         return filename
@@ -546,6 +550,8 @@
             self.text.event_generate("<<save-window-as-file>>")
         def save_a_copy(self, event):
             self.text.event_generate("<<save-copy-of-window-as-file>>")
+        def ispythonsource(self, filename):
+            return True #Change to False to mock OutputWindow.
     text = Text(root)
     text.pack()
     text.focus_set()
diff -r 095fbf03cad7 Lib/idlelib/OutputWindow.py
--- a/Lib/idlelib/OutputWindow.py	Wed Apr 02 15:51:38 2014 -0400
+++ b/Lib/idlelib/OutputWindow.py	Thu Apr 03 20:58:59 2014 +0530
@@ -20,7 +20,7 @@
 
     def ispythonsource(self, filename):
         # No colorization needed
-        return 0
+        return False
 
     def short_title(self):
         return "Output"