This to me is a bit counter-intuitive, but it's perhaps me just being used to the status quo...

When I see a gray box, that tells me nothing changed. In this case, something did change, though, only nothing was removed. As a patroller, I may quickly scan through the left side to see what changed (perhaps the last version was my version, hehe, and that's why I'm concerned about what words of mine were changed). In this situation, I would expect to see some indication of where a line changed, whether it was something added or removed, doesn't matter, I just need to know it was changed. I suspect other patrollers may operate in the same way.

Hypothetically, let's pretend this is a much bigger diff, and with moved paragraphs (I know those are handled separately, but bear with me, just a hypothetical example). In that case it may appear the gray content on the left was completely untouched since the corresponding block on the right isn't directly adjacent. That wouldn't be true, though, and I would be misled into thinking that block didn't change at all. In the small example in the above screenshot, it's easy to see what changed because it's there immediately on the right side, but that may not always be the case.

I believe we're going to ping some of the voters of the wish to ask what they think of this, which I definitely recommend. The proposed design might be great for newcomers, but patrollers who have to view diffs every day at high speeds should probably get the final say. However again, I imagine a lot of it is just patrollers being used to things looking one way, and any visual change will disrupt them, but (hopefully) only temporarily!

In short, gray boxes to me are only there for context (i.e. where am I looking in the source wikitext?). Seeing them means there were no changes to that block of text in any way.

Just my 2c. Please don't change designs solely because of my opinion :)

@MusikAnimal thanks for writing this up. We asked for feedback on the talk page and will be monitoring at well before we make any changes.

@dmaza You asked about moved paragraph changes, those should remain the same if a paragraph was moved. Let me know if that answers your question!

In T327193#8718187, @NRodriguez wrote:

@dmaza You asked about moved paragraph changes, those should remain the same if a paragraph was moved. Let me know if that answers your question!

It does. Thank you!