The Problem

A common mistake on my server goes like this:

• Admin copy-pastes a structure somewhere else
• Admin selects a pos1 on said structure
• Admin selects a pos2 on said structure, but actually re-selected pos1 instead. Edit now would engulf a very large area.
• Admin uses //set , not knowing the absurd number of blocks needed.
• Server overloads and crashes

A Solution

Make WorldEdit confirm the large-scale change, maybe with a "type the following code" captcha.

Alternatives

You could stop the edit entirely, but sometimes you do need to edit over a million blocks. (That, or the server hardware is powerful enough to handle AND undo such an action, but that's too rare)

Anything Else?

I was said admin.