Removed progress bar does not vanish completely

[fr34q]

If a progress bar is replaced by a new one (e.g. in nested loops) the old one will still need some space in the notebook (tested in JupyterLab) so the new bar is placed a bit beneath creating more and more empty space in nested loops.

Example:

Expected behavior: Progress bar vanishes (display: none) or is even removed from DOM entirely.

[Schneider1]

This is a bug of jupyterwidgets. Closed widgets leave an empty <div> container which is displayed by a blank space.

Solutions:

• fix the bug in jupyterwidgets itself
• do some JS magic to close the unneeded <div> cells (as I did it for the ipython notebook way of progressbar)
• Keep better track of all openend progressbars and always call clear_output()and display all progressbars
• Quick fix: Almost all routines that (I have written and) open a progress bar have the option progress_bar = False to supress the creation for PBs in the inner loop. I think for 1e5 iterations in 11secs, as shown in the picture, a PB is not needed

[fr34q]

Issue described here: https://github.com/jupyter-widgets/ipywidgets/issues/1845 and fixed in release 7.2 of ipywidgets

Therefore, to fix the issue upgrading local ipywidgets installation is sufficient: pip install --upgrade ipywidgets