A DESCRIPTION OF THE REQUEST :
Frequently a menu item is bound to action that is conditionally enabled. For example, the "Edit - Undo" action is enabled only if there are any undo records available. If the availability test is just in the Action.isEnabled() method for an action used to configure menu item, it is not automatically reflected in the dependent menu item. One must call Action.setEnabled every time the enabled state changes.

JUSTIFICATION :
The dynamic evaluation would simplify the notification process of the action availability: the notification wouldn't be needed in user code, user would need only to supply a callback availability test.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
The Action.isEnabled is evaluated every time before menu item is displayed or before its keystroke is pressed.
ACTUAL -
The copy of enabled state is stored in menu item, and is updated only upon explicit call of Action.setEnabled

---------- BEGIN SOURCE ----------
package bugs;

import java.awt.event.ActionEvent;

import javax.swing.AbstractAction;
import javax.swing.Action;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.KeyStroke;

public class MenuItemBug extends JFrame {

public MenuItemBug() {
JMenuBar bar = new JMenuBar();
final long now = System.currentTimeMillis();
JMenu edit = new JMenu("Edit");
AbstractAction action = new AbstractAction("Undo") {
public void actionPerformed(ActionEvent e) {
System.out.println("hit!");
System.exit(0);
}

public boolean isEnabled() {
return System.currentTimeMillis() > now + 1000;
}
};
action.putValue(Action.ACCELERATOR_KEY, KeyStroke
.getKeyStroke("control Z"));
edit.add(new JMenuItem(action));
bar.add(edit);
getRootPane().setJMenuBar(bar);
pack();
}

public static void main(String[] args) {
new MenuItemBug().setVisible(true);
}

}

---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
  To ensure that the enabled state of menu items is updated when the menu is made visible, you may subclass JMenu and override JMenu.setPopupMenu visible, and check for menu items, evaluate their actions' isEnabled, and update the items accordingly.

  To ensure that enabled state is evaluated dynamically upon key stroke, you may subclass JMenuItem, override its processKeyBinding, test if the key stroke matches to item's accelerator, and if so, refresh the enabled state.