@gnarf 

The reason to move it is for CSS overriding. Both of css rules this one and previous one match the conformation dialog. If we want to use `data-items=2` to have 2 button with 50% size, the following rule
`body[role="application"] [role="dialog"]:not([data-type="edit"]):not([data-type="action"]) menu:not([type="toolbar"]) button`
will override the 
`body[role="application"] [role="dialog"]:not([data-type="edit"]) menu[data-items="2"]:not([type="toolbar"]) button`
. So we will have 2 buttons with 100% width.

This is because they have the same specificity count, http://www.w3.org/TR/2011/REC-CSS2-20110607/cascade.html#specificity. They override each other sequentially.

I know it has another alternative to use, like !important or add :not([data-type="action"]) to the moved one. To preserve the original specificity, I choose move it.

Basically, I don't have any preference about this and more knowledge to say which one is better. I will love to do the change with your suggestion.