If you use datebox with format for date and time - format="short+short" - and also specific locale (I tried cs, sk, uk) and click on calendar picture for dropdown there is time picker at the bottom. This time picker shows everything depending on format but not hours. See attachment
It works for us, uk, de
I did not try everything

There is simple code for reproduction

<zk>
Datebox: <datebox id="db" cols="20" format="short+short" locale="cs" onCreate="self.value = new Date()"/>
<separator/>
</zk>