Tabs widget in pipeline_tuning become unwieldy with >10 tabs

[dokempf]

Could be solved by a "rolling" display, that only shows 10 even if there is more.

[dokempf]

I have tried this for way too long time, but run into trouble with my approach due to a bug in ipywidgets.Tab. I am closing this as wontfix for now - we have the delete controls to manage this as well.

[dokempf]

Michael repeatedly reported this as a major usability issue for him.

[dokempf]

The upstream issue that is making this really complicated is: jupyter-widgets/ipywidgets#2988

[dokempf]

This could be fixed with ipyflex, I think.