Following the MVVM listbox CRUD example (see http://books.zkoss.org/wiki/Small_Talks/2012/February/MVVM_in_ZK6:_Form_Binding), I've discovered a problem with the use of a Checkbox control inside the form.

If the Checkbox 'checked' attribute is bound to an attribute then on loading the ZUL (i.e. before a list box entry is selected) an error is throw:

Error writing 'checked' on type org.zkoss.zul.Checkbox crash