diff -r 0f17aed78168 Lib/idlelib/PyShell.py
--- a/Lib/idlelib/PyShell.py	Thu Aug 01 22:25:12 2013 +0200
+++ b/Lib/idlelib/PyShell.py	Fri Aug 02 23:40:22 2013 -0400
@@ -1549,34 +1549,35 @@
             # the file she wants to see. Lower the interpreter window when
             # there are open files.
             shell.top.lower()
+    else:
+        shell = flist.pyshell
+    if shell:
+        # handle remaining options:
+        if debug:
+            shell.open_debugger()
+        if startup:
+            filename = os.environ.get("IDLESTARTUP") or \
+                       os.environ.get("PYTHONSTARTUP")
+            if filename and os.path.isfile(filename):
+                shell.interp.execfile(filename)
+        if cmd or script:
+            shell.interp.runcommand("""if 1:
+                import sys as _sys
+                _sys.argv = %r
+                del _sys
+                \n""" % (sys.argv,))
+            if cmd:
+                shell.interp.execsource(cmd)
+            elif script:
+                shell.interp.prepend_syspath(script)
+                shell.interp.execfile(script)
 
-    shell = flist.pyshell
-    # handle remaining options:
-    if debug:
-        shell.open_debugger()
-    if startup:
-        filename = os.environ.get("IDLESTARTUP") or \
-                   os.environ.get("PYTHONSTARTUP")
-        if filename and os.path.isfile(filename):
-            shell.interp.execfile(filename)
-    if shell and cmd or script:
-        shell.interp.runcommand("""if 1:
-            import sys as _sys
-            _sys.argv = %r
-            del _sys
-            \n""" % (sys.argv,))
-        if cmd:
-            shell.interp.execsource(cmd)
-        elif script:
-            shell.interp.prepend_syspath(script)
-            shell.interp.execfile(script)
-
-    # Check for problematic OS X Tk versions and print a warning message
-    # in the IDLE shell window; this is less intrusive than always opening
-    # a separate window.
-    tkversionwarning = macosxSupport.tkVersionWarning(root)
-    if tkversionwarning:
-        shell.interp.runcommand(''.join(("print('", tkversionwarning, "')")))
+        # Check for problematic OS X Tk versions and print a warning
+        # message in the IDLE shell window; this is less intrusive
+        # than always opening a separate window.
+        tkversionwarning = macosxSupport.tkVersionWarning(root)
+        if tkversionwarning:
+            shell.interp.runcommand("print('%s')" % tkversionwarning)
 
     while flist.inversedict:  # keep IDLE running while files are open.
         root.mainloop()