Steps to Reproduce
1. click the button to trigger an error message on the textbox out of the viewport
2. scroll down to show the textbox
Current Result
the textbox has red borders but no error box shows
Expected Result
the error box shows
Debug Information
1. caused by the fix of ZK-4408
2. https://www.zkoss.org/wiki/ZUML_Reference/ZUML/Namespaces/Client_Attribute/Data-Scrollable