tasks example failure

[ddale]

I get the following when I try to run the tasks example from master, on OS X Lion (with qt4/PyQt4 and no wx):

[~/Projects/ets/envisage/examples/plugins/tasks/attractors](master)
darren@minerva $ python run.py 
Exception occurred in traits notification handler.
Please check the log file for details.
Exception occurred in traits notification handler for object: <plot_3d_pane.Plot3dPane object at 0x11d453ef0>, trait: active_model, old value: None, new value: <model.lorenz.Lorenz object at 0x11d4536b0>
Traceback (most recent call last):
  File "/Users/darren/Library/Python/2.7/lib/python/site-packages/traits-4.0.1-py2.7-macosx-10.7-x86_64.egg/traits/trait_notifiers.py", line 505, in rebind_call_0
    self.dispatch( getattr( self.object(), self.name ) )
  File "/Users/darren/Library/Python/2.7/lib/python/site-packages/traits-4.0.1-py2.7-macosx-10.7-x86_64.egg/traits/trait_notifiers.py", line 448, in dispatch
    handler( *args )
  File "/Users/darren/Projects/ets/envisage/examples/plugins/tasks/attractors/plot_3d_pane.py", line 49, in _update_scene
    self.scene.mlab.clf()
  File "/Users/darren/Library/Python/2.7/lib/python/site-packages/traits-4.0.1-py2.7-macosx-10.7-x86_64.egg/traits/trait_types.py", line 2776, in create_default_value
    return klass( *args[1:], **kw )
  File "/Users/darren/Library/Python/2.7/lib/python/site-packages/mayavi-4.0.1-py2.7-macosx-10.7-x86_64.egg/mayavi/tools/mlab_scene_model.py", line 41, in __init__
    self.engine.current_scene = current_figure
  File "/Users/darren/Library/Python/2.7/lib/python/site-packages/mayavi-4.0.1-py2.7-macosx-10.7-x86_64.egg/mayavi/core/engine.py", line 522, in _set_current_scene
    self._current_scene = scene
  File "/Users/darren/Library/Python/2.7/lib/python/site-packages/traits-4.0.1-py2.7-macosx-10.7-x86_64.egg/traits/trait_types.py", line 2690, in validate
    self.validate_failed( object, name, value )
  File "/Users/darren/Library/Python/2.7/lib/python/site-packages/traits-4.0.1-py2.7-macosx-10.7-x86_64.egg/traits/trait_types.py", line 2553, in validate_failed
    self.error( object, name, value )
  File "/Users/darren/Library/Python/2.7/lib/python/site-packages/traits-4.0.1-py2.7-macosx-10.7-x86_64.egg/traits/trait_handlers.py", line 168, in error
    value )
TraitError: The '_current_scene' trait of an Engine instance must be an implementor of, or can be adapted to implement, Scene, but a value of None <type 'NoneType'> was specified.
ERROR:traits:Exception occurred in traits notification handler for object: <plot_3d_pane.Plot3dPane object at 0x11d453ef0>, trait: active_model, old value: None, new value: <model.lorenz.Lorenz object at 0x11d4536b0>
Traceback (most recent call last):
  File "/Users/darren/Library/Python/2.7/lib/python/site-packages/traits-4.0.1-py2.7-macosx-10.7-x86_64.egg/traits/trait_notifiers.py", line 505, in rebind_call_0
    self.dispatch( getattr( self.object(), self.name ) )
  File "/Users/darren/Library/Python/2.7/lib/python/site-packages/traits-4.0.1-py2.7-macosx-10.7-x86_64.egg/traits/trait_notifiers.py", line 448, in dispatch
    handler( *args )
  File "/Users/darren/Projects/ets/envisage/examples/plugins/tasks/attractors/plot_3d_pane.py", line 49, in _update_scene
    self.scene.mlab.clf()
  File "/Users/darren/Library/Python/2.7/lib/python/site-packages/traits-4.0.1-py2.7-macosx-10.7-x86_64.egg/traits/trait_types.py", line 2776, in create_default_value
    return klass( *args[1:], **kw )
  File "/Users/darren/Library/Python/2.7/lib/python/site-packages/mayavi-4.0.1-py2.7-macosx-10.7-x86_64.egg/mayavi/tools/mlab_scene_model.py", line 41, in __init__
    self.engine.current_scene = current_figure
  File "/Users/darren/Library/Python/2.7/lib/python/site-packages/mayavi-4.0.1-py2.7-macosx-10.7-x86_64.egg/mayavi/core/engine.py", line 522, in _set_current_scene
    self._current_scene = scene
  File "/Users/darren/Library/Python/2.7/lib/python/site-packages/traits-4.0.1-py2.7-macosx-10.7-x86_64.egg/traits/trait_types.py", line 2690, in validate
    self.validate_failed( object, name, value )
  File "/Users/darren/Library/Python/2.7/lib/python/site-packages/traits-4.0.1-py2.7-macosx-10.7-x86_64.egg/traits/trait_types.py", line 2553, in validate_failed
    self.error( object, name, value )
  File "/Users/darren/Library/Python/2.7/lib/python/site-packages/traits-4.0.1-py2.7-macosx-10.7-x86_64.egg/traits/trait_handlers.py", line 168, in error
    value )
TraitError: The '_current_scene' trait of an Engine instance must be an implementor of, or can be adapted to implement, Scene, but a value of None <type 'NoneType'> was specified.

[prabhuramachandran]

Sorry my checkin on Mayavi has broken this. I'll fix it shortly.

[prabhuramachandran]

Thanks, I've pushed a fix in mayavi.