Property:

class.mold

Default: none
[Since 5.0.0]

It specified the default mold of the specified component. The property name is a concatenation of the class name of the component and mold. For example, the property for the button’s default mold is called org.zkoss.zul.Button.mold.

<library-property>
    <name>org.zkoss.zul.Button.mold</name>
    <value>trendy</value>
</library-property>