Using Message Dialogues in Applets
It is easy to implement a message dialogue, which has only one button ("OK") with in-built event handling. We show first a plain message followed by the code.

Message dialog applet (280 x 180) in action
namespace msg_dialog_demo; interface uses java.util, java.applet.*, java.awt.*, javax.swing; type MsgDialogDemo = public class(Applet, ActionListener) private btnMessage : Button; public method init; override; method actionPerformed(e : ActionEvent); end; implementation method MsgDialogDemo.init; begin Background := Color.green.darker; btnMessage := new Button('Message Dialog'); add(btnMessage); btnMessage.addActionListener(self); end; method MsgDialogDemo.actionPerformed(e : ActionEvent); begin if e.getSource = btnMessage then begin JOptionPane.showMessageDialog(self, 'Hello World!', 'Obligatory First Greeting', JOptionPane.PLAIN_MESSAGE); end; end; end.You can replace JOptionPane.PLAIN_MESSAGE with JOptionPane.ERROR_MESSAGE (to show an "X" icon), with JOptionPane.WARNING_MESSAGE ("!" icon) or with JOptionPane.INFORMATION_MESSAGE ("i" icon) e.g.

Information message dialog