OK, I open a file, split the screen to have two copies of the same file. Lock the top and start editing the bottom. Can Scrivener edit the bottom screen WITHOUT simultaneously changing the top, original version? Yeah, I know I can take a snapshot, but that doesn’t help me in visually comparing the edit to the original which I think is important for immediate visual sampling of the changes. If this is not available, then please consider this as possible future feature. Thank you.
No, you’re editing the same doc, and seeing it via two separate views, so your edits will apply to both views. That’s only one doc you’re looking at. It works in Scrivener exactly the same way as it would in Word if you had the same document open in two different windows.
What I do in this scenario is make a copy of the original document to compare to, and keep the version I want to edit in one pane and the original in the other for comparison.
Best,
Jim
And regarding your request, the next version of Scrivener (currently in beta) will allow for improved referencing of Snapshots. You’ll be able to load a snapshot into a split view for side-by-side comparison, show change tracking markings in the snapshot for even easier comparison, or load the snapshot into a Copyholder, which is another new feature that allows for you to load auxiliary text into the current split—useful if you’ve already got a split view and don’t want to disturb the other side with your editing process.
Thank you Jim for your tip, and thank you Amber for the good news of comparing a file to a snapshot. I look forward to that. 
Ditto! 