Users should be able to insert an email address at an arbitrary location in the TO list. This is not possible. Part of the hassle is the fact every recipient is listed in a separate field and therefore it's not possible to edit several recipients at once. I realize this UX change was probably the solution to the dreaded first-comma-last-name problem but it's a serious P.I.T.A. Currently Enter, Shift+Enter and Alt+Enter all advance to the next field (Ctrl+Enter is send after confirmation by default). One of them should be commandeered to "insert" a new field at the current cursor position. Enter is the most logical but Shift+Enter would be acceptable in consideration of UX consistency. I quoted insert because it should really be a split operation. That means Shift+Enter with the cursor at the beginning of existing text inserts a new field before; cursor at end of existing text inserts new field after; and cursor in the middle results in two fields with preceding text in original field, following text in new field and cursor at start of new field.

Interesting idea.

I think basically bug 440377. Not worth doing it any other way.