idle: Options -> Configure IDLE crashes with TclError: expected integer but got ""

[Etienne Papegnies]

ouroumov@Box:~/Desktop$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 16.04 LTS
Release: 16.04
Codename: xenial

ouroumov@Box:~/Desktop$ apt-cache policy idle
idle:
  Installed: 2.7.11-1
  Candidate: 2.7.11-1
  Version table:
 *** 2.7.11-1 500
        500 http://fr.archive.ubuntu.com/ubuntu xenial/main amd64 Packages
        500 http://fr.archive.ubuntu.com/ubuntu xenial/main i386 Packages
        100 /var/lib/dpkg/status

Expected behavior:

After opening IDLE from the terminal by typing "idle", going to Options -> Configure should open the configuration window.

Actual Behavior:

Terminal shows a Python Traceback and nothing happens.
Traceback:

ouroumov@Box:~/Desktop$ idle
Exception in Tkinter callback
Traceback (most recent call last):
  File "/usr/lib/python2.7/lib-tk/Tkinter.py", line 1540, in __call__
    return self.func(*args)
  File "/usr/lib/python2.7/idlelib/EditorWindow.py", line 543, in config_dialog
    configDialog.ConfigDialog(self.top,'Settings')
  File "/usr/lib/python2.7/idlelib/configDialog.py", line 72, in __init__
    self.LoadConfigs()
  File "/usr/lib/python2.7/idlelib/configDialog.py", line 1103, in LoadConfigs
    self.LoadFontCfg()
  File "/usr/lib/python2.7/idlelib/configDialog.py", line 1005, in LoadFontCfg
    self.SetFontSample()
  File "/usr/lib/python2.7/idlelib/configDialog.py", line 883, in SetFontSample
    self.labelFontSample.config(font=newFont)
  File "/usr/lib/python2.7/lib-tk/Tkinter.py", line 1329, in configure
    return self._configure('configure', cnf, kw)
  File "/usr/lib/python2.7/lib-tk/Tkinter.py", line 1320, in _configure
    self.tk.call(_flatten((self._w, cmd)) + self._options(cnf))
TclError: expected integer but got ""

Additional information:

Also affects idle3 binary.

Ubuntu MATE 16.04 fully up to date as of 2016-07-04

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Launchpad Janitor (janitor)]

[Expired for python-defaults (Ubuntu) because there has been no activity for 60 days.]