if zsh prints out a list (eg. on an ambiguous completion), it reuses the old prompt instead of printing a new one underneath the list; this breaks menucompletion if turned off
complete_aliases
don't expand aliases _before_ completion has finished
complete_in_word
if unset the cursor is set to the end of the word if completion is started
list_ambiguous
complete as much of a completion until it gets ambiguous.
glob_complete
cycle through globbing matches like menu_complete
rec_exact
in completion, recognize exact matches even if they are ambiguous.