Interesting... I see that it works on Chrome and IE but on Firefox I see the error....
For example for the combobox at:
http://www.jeasyui.com/demo/main/index.php?plugin=ComboBox&theme=default&dir=ltr&pitem=I attach an image - as you can see the combobox is a text item and does not show all of the other possible values from the drop down...
Weird thing is that on my development machine (local host) firefox is showing the combobox properly...