Steps to Reproduce

1. click the "selectAll" checkbox in the header of a Listbox

Current Result

java.lang.IndexOutOfBoundsException: Index: 1
at java.base/java.util.AbstractSequentialList.get(AbstractSequentialList.java:90)
at org.zkoss.zul.Listbox$1.get(Listbox.java:391)
at org.zkoss.zul.Listbox$1.get(Listbox.java:385)
at org.zkoss.zul.Listbox.service(Listbox.java:3729)
at org.zkoss.zk.ui.impl.DesktopImpl.service(DesktopImpl.java:861)

Expected Result

no error

Debug info

• 9.6.3 doesn't have this bug
• caused by the fix of ZK-2658

Workarounds

Two options, apply either but not both

Workaround #1

Use JS to prevent select all event if the content is empty:

zk-5483.js

Workaround #2

Java side Listbox override
Listbox.java