Steps to Reproduce

Use iPad Air Safari to test B70-ZK-2978.zul
1. load this page
2. open 2 groupbox
3. should appear vertical scrollbar

await t.expect(await ztl.hasVScrollbar({locator:Selector(() => jq('.menuGroupboxContainer')[0])})).ok();

Current Result

It returns false.

Expected Result

It returns true.

Debug Information

In mobile, if <custom-attributes org.zkoss.zul.nativebar="false"/> is used, iScroll will be used.

And the native bar in mobile doesn't occupy any space, so offsetHeight - clientHeight is always 0. Use scrollHeight is safer.

Workaround