Aleksandrs Saveljevs has reported a couple of problems with the screen clock:

"(1) Clock element links to zabbix.com. It probably shouldn't.
(2) If clock element with "Host time" is present in a templated screen, then on the host level it will try to show data from the item in the template. It should show data from host's item.
(3) Also, the clock element shows technical host name. It should show visible host name."

(4) I also have a hunch, that the item key, that the user chooses when creating a clock, is actually hard coded some were in flash, because it's not passed to the flash object, only the host name is. I'll try to confirm it in the near future.