use cursor DOWN to change the current selection to select 'ccc'
everytime when pressing up/down an onSelect/onChange event is fired to the server
(this doesn't happen when simply typing 'ccc', here the events only trigger during onBlur)
When using the mouse it is possible to chose an element without firing the events for intermediate results
provide an options to disable eagerly sent events (and send event when leaving the combobox onBlur) For scenarios where only the final selection is required (and intermediate selections only trigger unwanted http requests)
this becomes especially more apparent when using autodrop="true", indicating more a preview than the actual selection before confirming with ENTER
ZK-2548 could be related