Comm code is not run in the same context as notebook code

[jdfreder]

Discovered because of #4983

Things like tracebacks are not getting displayed in the notebook. There is a lot of logic in the zmq shell stuff that doesn't get ran for comm msgs...

[ellisonbg]

Another thing that doesn't work is the extra logic that the inline mpl backend adds for autodisplaying plots at the end of a cell.

[jdfreder]

Related to #5064

[jdfreder]

Addressed by #5188

[jdfreder]

Reopening, this is still a problem, see jupyter-widgets/ipywidgets#44

[Carreau]

Closing as this issue is not in IPython itself and if still problematic and relevant should be opened on the right repository. This will allow to keep the number of opened issue on the IPython repo under control.

Feel free to keep commenting or reopen if necessary.

Thanks.