The editor 4Coder in the Handmade Hero streams has the first novel way to indicate scope that I’ve seen for a long time:
In case it’s not clear, rotated vertical labels are drawn in the whitespace showing the clause that identifies the scope - conditional statement, function name etc.
This seems like a genuinely useful way to use whitespace.
It was hard to find a decent image so I grabbed that from the stream. but the stream makes it very clear