original post:
http://www.zkoss.org/forum/listComment/18701

Reproducing Steps:

1. you can use fiddle to run user-provided example
2. choose 5.0.9, run
3. select random 3 item, click print, it prints in order as original listing
4. choose 5.0.10 or 6.0.0, repeat step 3, you'll find it prints selected item in reversed selected order.
i.e. you select item 3, item 4, item 5, it prints item 5, item 4, item 3