I'm using zsh 5.3.1

I might have found a minor bug when running reset-prompt with a two-line
prompt while displaying completion info. This is the complete .zshrc needed
to reproduce the problem:

# ==========================

zmodload -i zsh/sched

schedprompt() {
    zle && zle reset-prompt
    sched +5 schedprompt
}
schedprompt

autoload -U compinit
compinit

PS1=$'first\n> '

# ===========================

As you can see, it sets up the prompt to redraw every five seconds, and
also sets up a two-line prompt.

Now do this:
1) Type 'ls -<tab>'  (the completion list for ls options is displayed)
2) Wait a few seconds (so that the prompt is redrawn)
3) Type any letters

You will observe that the letters typed in the last item are displayed one
line _above_ where it is supposed to be. A few seconds later, again when
the prompt is redrawn, the text is repositioned in the right place.

This seems like a bug to me.