– C.C. & K.R.
No. Never ever. Both your coat and your vest are to be worn with the bottom button undone in any and all circumstances. As far as the rest of the buttons go, feel free to wear them either way when you are seated, but do them back up as soon as you leave your chair if you are wearing a suit or a sport coat. Casual or deconstructed blazers and jackets can, of course, remain unbuttoned 24-7. They’re easy that way.