Steps to Reproduce

https://zkfiddle.org/sample/bjr8nk/1-Event-with-keyCode-0-closes-popups

Run fiddle

Open bandbox (click on bandbox button, or alt+down in input)

wait for the interval to send a keyboardevent with a keycode of 0

Current Result

popup is closed

Expected Result

Unsure, need to clarify use case

Debug Information

https://github.com/zkoss/zk/blob/master/zul/src/archive/web/js/zul/inp/ComboWidget.js#L632-L636

The _doKeyDown function on comboWidget actively listend to event keyCode == 0.

This appear to be safari-specific, but current test were not able to replicate instances of keyCode 0 on tab or alt-tab.

Need to review if this is still relevant, or a holdout from older safari / webkit versions

Workaround