!592 // auto-import
!614 // actionListener {
!619 // standard classes (LetterLayout, CenteredLine)
!1000280 // class x12

import java.awt.*;
import java.util.List;

public class main {
  public static void main(String[] args) {
    JFrame frame = new JFrame("JavaX IDE!");
    
    final JTextArea textArea = new JTextArea();
    JButton btnGo = new JButton("Go!");
    btnGo.addActionListener(actionListener {
      try {
        File ioBaseDir = new File(".");
        File src = x12.TempDirMaker_make();
        x12.saveTextFile(new File(src, "main.java").getPath(), textArea.getText());
        x12.javax4(src.getPath(), ioBaseDir, false, false);
      } catch (Throwable e) {
        popupError(e);
      }
    });

    JPanel panel = new JPanel(new LetterLayout("T", "T", "B").setBorder(10));
    panel.add("T", new JScrollPane(textArea));
    panel.add("B", new CenteredLine(btnGo));
    frame.add(panel);
    
    frame.setBounds(100, 100, 500, 400);
    frame.setVisible(true);
    exitOnFrameClose(frame);
  }
  
  static void exitOnFrameClose(JFrame frame) {
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  }
  
  static void popupError(final Throwable throwable) {
    throwable.printStackTrace(); // print stack trace to console for the experts
    SwingUtilities.invokeLater(new Runnable() {
      public void run() {
        String text = throwable.toString();
        //text = cutPrefix(text, "java.lang.RuntimeException: ");
        JOptionPane.showMessageDialog(null, text);
      }
    });
  }

}

Began life as a copy of #613