Steps to Reproduce

run the fiddle, click the [create] button

https://zkfiddle.org/sample/opq7sg/1-adding-listbox-with-item-renderer-in-posted-eventlistener

Current Result

the listbox renders without any listitems

Expected Result

3 listitems rendered "aaa", "bbb", "ccc"

Debug Information

the issue happens specifically when setting the model and itemRenderer in an event listener for a custom event triggered via postEvent from doAfterCompose of a composer instance

the zkau response doesn't contain the listitems.
at server side the listbox dataloader implements a Cropper that returns no items to be rendered in this scenario

Workaround

1. don't use an ListItemRenderer,
2. call setItemRenderer before setModel
3. detach/re-attach the listbox before setting the model/itemrenderer