Currently you first have to select the people from your address book, then you have to write the email.
Instead, when clicking on the "To:" link in the compose window, it should bring the address book, not the current people you already have in your To, cc or bbc fields; I really don't get the point of this option now except to switch names from To, Cc or Bcc, something which you can easily do anyway with copy-paste.
