ConsoleWidget(): `RuntimeError: You can't initialize an object twice!` with traitlets master

from qtconsole.qt import QtGui
from qtconsole.console_widget import ConsoleWidget
QtGui.QApplication.instance() or QtGui.QApplication([])
cw = ConsoleWidget()

Results in

Traceback (most recent call last):
  File "../../canopy-jupyter/scratch.py", line 4, in <module>
    cw = ConsoleWidget()
  File "/home/pankaj/work/enthought/jupyter/qtconsole/qtconsole/console_widget.py", line 214, in __init__
    LoggingConfigurable.__init__(self, **kw)
  File "/home/pankaj/work/enthought/jupyter/traitlets/traitlets/config/configurable.py", line 74, in __init__
    super(Configurable, self).__init__(**kwargs)
  File "/home/pankaj/work/enthought/jupyter/traitlets/traitlets/traitlets.py", line 946, in __init__
    super(HasTraits, self).__init__()
RuntimeError: You can't initialize an object twice!

with traitlets master. This is because of mixing old-style and __init__ call and super __init__ call. Simple git bisect indicated the causal commit to be: https://github.com/ipython/traitlets/pull/174

A solution would be to do things similar to SuperQObject https://github.com/jupyter/qtconsole/blob/master/qtconsole/util.py#L48 , i.e. a SuperQWidget, and probably any other Super qobject subclass which needs to be used in multiple inheritance with HasTraits.

[pshchelo]

Downgrading traitlets to traitlets==4.1.0 solves the issue.

[minrk]

I opened #114, which seems to fix this.