Scrolling for a Spark lengthy job progress bar

[diocas]

Requested by Michał (UCA-386):

I am working with a large dataset (1000+ signals) queried for several periods of time with NXCALS. The query results in tens of load and collect jobs. As a result the progress bar under the cell is quite long making difficult the use of the notebook (see attached). For a longer query, my browser couldn't handle hundreds of lines appearing.

Thus I'd like to suggest adding an internal scroll bar and/or grouping similar tasks into a single subtree.