With PropertyEditors and Customizers u can provide u'r own interface to the user to change specific properties. for eg., when u click on font in the propertysheet of beanbox, u get a particular customized dialog box. This dialog is different than that which pops up when u click on background. similarly, if u have seen the molecule bean, the property "moloculeName" has been customized to be a dropdown list. u could rewrite the customizer for the Molecule bean to popup a dialog box instead of a dropdown menu. For such customizations (ie., providing u'r own interface to the user of this bean to change the properties of that bean) we can use the Customiser or PropertyEditor Interfaces.