Can a footnote be kept open while

Not the popup, if that's your question.

But at least on the Mac, you can quickly snap to footnote view with shift-Cmd-P (and then back).

Yep. Too bad. The popup not to be confused with the baseball term. Go Phillies.

It sure would make it easier to keep it open while referencing. 

Thanks.

Can a footnote/endnote be kept open while searching for references?

Not as a popup. However, you can switch from "0" columns to "1" column and have footnotes at the bottom of the page. 

That might work. Thanks.

Can a footnote/endnote be kept open while searching for references?

Not as a popup. However, you can switch from "0" columns to "1" column and have footnotes at the bottom of the page. 

That might work. Thanks.

or use Power Lookup without changing your reading view.