Errorbox still not shown when WrongValueException is thrown on a multiline textbox

Reproducible steps:

1. Load the zul page below
2. Click on "Wrong value" button to throw WrongValueException on the multiline textbox

<zk>
    <button label="Wrong value" onClick='throw new WrongValueException(textbox, "error message");'/>
    <textbox id="textbox" multiline="true"/>
</zk>

Expected result:

The textbox should have red border, and an errorbox appears with the "error message" message.

Actual result:

The textbox has red border, but an errorbox does not appear.