I have tcl/tk 8.6.0 installed here. Both Python versions below
are build from source.

I'm using LANG=en_US.iso88591 here if that matters.

When opening a file in Idle with 
python-3.3.1 revision: c08bcf5302ec

or

python-3.4.0a0 (default:3a110a506d35) (HG version)

I get
Failed to load extension 'CodeContext'
Traceback (most recent call last):
  File "/home/jarausch/GenToo/LOC/TEST/Python/cpython/Lib/idlelib/EditorWindow.py", line 1034, in load_standard_extensions
    self.load_extension(name)
  File "/home/jarausch/GenToo/LOC/TEST/Python/cpython/Lib/idlelib/EditorWindow.py", line 1055, in load_extension
    ins = cls(self)
  File "/home/jarausch/GenToo/LOC/TEST/Python/cpython/Lib/idlelib/CodeContext.py", line 49, in __init__
    self.toggle_code_context_event()
  File "/home/jarausch/GenToo/LOC/TEST/Python/cpython/Lib/idlelib/CodeContext.py", line 66, in toggle_code_context_event
    padx += int(str( widget.pack_info()['padx'] ))
  File "/home/jarausch/GenToo/LOC/TEST/Python/cpython/Lib/tkinter/__init__.py", line 1919, in pack_info
    self.tk.call('pack', 'info', self._w))
TypeError: Can't convert '_tkinter.Tcl_Obj' object to str implicitly