This allows to have a custom widget like the following, which would
additionally accept the line, but only in case of entries being
selected:

    fzf-file-widget-with-accept() {
      zle fzf-file-widget
      if [[ "$?" == 0 ]] && (( $#BUFFER )); then
        zle accept-line
      fi
    }
    zle     -N   fzf-file-widget-with-accept
    bindkey '\e^T' fzf-file-widget-with-accept

With this `<C-a>t` will launch fzf, and simulate the pressing of "Enter"
afterwards.