Actually I don't like the way multi part editing is display/controlled in Studio One so I don't think one hotkey (that you don't know if you don't read it in the manual or in forum threads) makes it less confusing.
I really like how it's done in Cubase:
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You just have one dropdown list that contains all selected events and you can easily selected that one you want to edit. The track list in the editor is a useful thing but all those different symbols (white circle, pensil, italic) makes it very confusing. For me a simple list like in Cubase would be much smarter.