SWT Java Tutorial

If pack is set to true, all controls have the same size, which is the size required to accommodate the largest preferred height and the largest preferred width of all the controls.
The default value is true.

import org.eclipse.swt.SWT;
import org.eclipse.swt.layout.RowLayout;
import org.eclipse.swt.widgets.Button;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.List;
import org.eclipse.swt.widgets.Shell;
public class RowlLayoutPack {
  public static void main(String[] args) {
    Display display = new Display();
    final Shell shell = new Shell(display);
    RowLayout rowLayout = new RowLayout();
    rowLayout.pack = false;
    
    shell.setLayout(rowLayout);
    Button button1 = new Button(shell, SWT.PUSH);
    button1.setText("button1");
    List list = new List(shell, SWT.BORDER);
    list.add("item 1");
    list.add("item 2");
    list.add("item 3");
    Button button2 = new Button(shell, SWT.PUSH);
    button2.setText("button #2");
    
    shell.setSize(450, 100);
    shell.open();
    while (!shell.isDisposed()) {
      if (!display.readAndDispatch()) {
        display.sleep();
      }
    }
    display.dispose();
  }
}