case $TERM in screen*)
   PROMPT_COMMAND='perl -e '\''print "\e_$ENV{USER}\@$ENV{HOSTNAME}:$ENV{PWD}/\e\\"'\'
esac

" set GNUScreen's hardstatus line
function! SetScreenHardstatus()
   exec ":!echo -e '\033_" . $USER . "@" .$HOSTNAME . ":" . expand("%:p") . "\033\\'\"
endfunction
au BufEnter * silent call SetScreenHardstatus()