The code:
public class Try_Grow_01 {
    public static void main(String[] args) {
        JFrame frame = new JFrame();
        frame.setLayout(new MigLayout("fill, debug", "[fill]5[5]"));
        frame.add(new JButton("one"), "");
        frame.add(new JButton("two"), "");
        frame.add(new JButton("three"), "");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }
}
result is

i.e. two right cells also grow, while I want them not to.
How to accomplish?
                        
If you want the first cell grow and fill all available space then you must create the
MigLayoutas follows:If you want the first cell grow but without fill the available space then you must create the
MigLayoutas follows:Take a look to page 6 of Quick Start guide