Documentation
Client Properties
What is a client property?
Swings base class for all components, javax.swing.JComponent,
provides following methods that allows you to set and get user-defined
properties:
public final Object getClientProperty(Object key);
public final void putClientProperty(Object key, Object
value);
Some Swing components use client properties to change their
behavior. E.g. for JLabel you can disable HTML display with label.putClientProperty("html.disable",
Boolean.TRUE); You can use client properties to store any
information in components. Visit Finally...
Client Properties You Can Use on Ben Galbraith's Blog for a use
case.
Define client properties
You can define client properties on the Client Properties page in the Preferences dialog.
Edit client properties
If you've defined client properties, JFormDesigner shows them in the Properties view, where you can set the values of the client properties.

