Version 0.5.0+ no longer displays output after widget interaction

I have not labeled this as a "bug report" as I am not sure whether this is a new feature or regression.

I am developing a package for the processing of NMR spectra that makes extensive use of the ipympl backend:
https://github.com/NMRPy/nmrpy

As part of this there are a number of widgets (interactive matplotlib graphs) for phasing and peak picking of the NMR spectra. Some of these widgets print output to the cell output area (below the ipympl widget) after user interaction, using simple `print()` function calls in the code. In some cases further user input is required for which I have made use of an `ipywidgets.FloatText()` which is then also displayed in the output area.

**As of version 0.5.0 this cell output area is no longer displayed.** The widget interaction with the ipympl graphs still works but the text output from `print()` calls and the ipywidgets output are not there.

- Is this intentional or a regression?
- If intentional, is there a way to get the output area back, or an alternative where to direct text output after interaction with a graph (or instantiate an `ipywidgets` widget) so that it is displayed to the user?

This functionality is crucial to my application and currently I am thus stuck with using ipympl<0.5.0. BTW this is using notebook, not jupyterlab.

Compare ipympl 0.5.0 with a pre-0.5.0 version in a classic Jupyter Notebook, reproducing interaction with an ipympl graph, print(), and ipywidgets.FloatText(). Trace how widget output is displayed after interaction; done means printed text and instantiated widgets appear in the cell output area again or the supported replacement is documented.

Written by the indexing model from the issue text.