The Scratchbook functionality will place content from many dataset link-outs into pop-up windows, instead of the center panel. Note that all actions/link-outs are not activated or even appropriate for this function, but many are. One use case is visually comparing the content of more than one dataset side-by-side - with the added benefit of not losing your place within a larger history. Please note that if the dataset is in compressed format, it is not displayed in the "peek" view or with scatchbook (at this time).
Give it a try to see how this works exactly. Start with the "View Dataset" option (eye icon) as an example. It will work with one dataset, but try testing with at least two datasets to review the utility. I tend to use this function for some tasks and not others, depending on what I am doing. It is very simple to use. Just click on the sketchbook icon in the masthead to toggle on/off, real time.
I think you'll find this functionality super useful from both my experience and the feedback from others using it.
Take care, Jen, Galaxy team