A band box. A bank box consists of an input box ( {@link Textbox} anda popup window {@link Bandpopup}. It is similar to {@link Combobox} except the popup window could haveany kind of children. For example, you could place a textbox in the popup to let user search particular items.
Default {@link #getZclass}: z-bandbox.(since 3.5.0)
Events: onOpen
Developers can listen to the onOpen event and initializes it when {@link org.zkoss.zk.ui.event.OpenEvent#isOpen} is true, and/orclean up if false.
Note: to have better performance, onOpen is sent only if a non-deferrable event listener is registered (see {@link org.zkoss.zk.ui.event.Deferrable}).
@author tomyeh