frame.js

importClass(Packages.javax.swing.JComponent);
importClass(Packages.javax.swing.JFrame);
importClass(Packages.javax.swing.JLabel);
importClass(Packages.java.awt.Color);

var frame=new JFrame('Foo!');
var comp=new JComponent(){
	paintComponent:function(g){
	    print('painted');
	    g.setColor(Color.RED);
	    g.drawLine(0,0,100,100);
	}
    };

//frame.getContentPane().add(new JLabel('foo'));
frame.getContentPane().add(comp);
frame.pack();
frame.setVisible(true);