Edit correcting wrong information in original answer and adding example code has been rolled back because “it changed too much in the original post”

Question

One edit I did in a Stack Overflow question was approved by two reviewers and rejected by a third, and this actually ended up in my change being rolled back.

I don't think my edits should be automatically accepted, and I understand that my point of view may be different than that of other people (and I've also read other Metas and blog posts on this matter), but I can't understand the reason of the rejection/rollback.

The reviewer that rejected the change motivated the action with the following reason:

This edit changes too much in the original post; the original meaning or intent of the post would be lost.

Which generally speaking is a fine reason, but in the specific case I feel it's wrong:

• The original answerer said that, as far as he knew, there was no way to access the Control inside the DataGridViewCell besides inside the DataGridView.EditingControlShowing event handler: in my edit I deleted this statement, and added sample code that proves that it is possible (and how) to always access the Control.
• The answer still answers the original question, and it doesn't change the original meaning and scope of the answer
• The code sample that I added also has the benefit of explaining how to exploit what the first sentence of the answer said, which was missing in the original answer.

That being said, it is true that my edit doubles the length of the answer (which may be seen as changing much of it), but it also true that the edit improves, completes and makes the original answer easier to understand and apply in actual code.

What should I do this time and in the future in a similar situation?

Disclosure/note: I also happen to have another questionable rollback being discussed in another Meta Question of mine, but it covers a different scenario, that's why I posted this question.

In the other case I also ended up making a long discussion in the answer's comment section, which is not really useful and this time I ended up posting directly my concern here on Meta Stack Overflow.

Answer 1

The threshold between editing someone's answer to improve it and posting your own answer is somewhat subjective, so it isn't surprising that different reviewers have different opinions. Here's my analysis of your edit:

• The original answer is well-written, with both English and a short code sample.
• The original answer is accepted, so it has been useful to someone.
• There are no comments under the answer pointing to a flaw that the suggested edit might be correcting.
• The edit would approximately double the length of the answer.
• The edit has correct English and formatting.
• The edit concerns a special case: when a view or cell is read-only.
• The edit is substantial enough that it could be posted as an answer on its own (addressing the read-only case).

I don't know the subject matter. In principle, this should mean that I should pass on the suggestion. Unfortunately, the suggested edit review queue is short-staffed, and the list cannot be sorted by tag, so the few of us who hang out there sometimes have to take a decision without subject knowledge. If I had answers to the following, it would influence my decision:

• Is the special case that the suggestion addresses common?
• Are the additional code and accompanying explanation correct?

What clinches it for me is the edit is substantial enough that it could be posted as an answer on its own. So I would reject it, as radical change or invalid edit or with a custom message “please post this as a separate answer”.

If I knew the answers to the two questions above to be yes, I might approve the suggestion. Might, note: it would be borderline even then.

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As a more general note, please keep in mind that reviewers might not be fully familiar with the subject of the post. They often wouldn't know enough to answer the question, and sometimes they won't even know the programming language that the code is written in. It helps if your edit comment explains what you did to an untrained audience. If you do more than fix spelling, formatting or typos, you should leave a comment for the original author, too.

Don't be shy of correcting factual errors (as long as you aren't changing so much of the post that you should instead be downvoting it and posting a separate correct answer), but do take care to make it clear why your changes are correct and necessary (in the edit comment or in a comment on the post: never add things like “edit by X: …” to the post).