The following is for a custom window, haven't checked for a dialog yet:
alias clockStart {
window -c @Clock
window -z @Clock
echo @Clock $asctime(H:nn:ss)
.timerclock 0 1 //rline @Clock 1 $!asctime(H:nn:ss)
}
alias clockStop {
timerclock off
window -c @Clock
}
That works, however, as said, it's in a separate custom window, so I'm not so sure it is all that useful. You can tile your windows to see it all the time

Where did you originally want it displayed?