java version "1.8.0-ea"
Java(TM) SE Runtime Environment (build 1.8.0-ea-b101)

A slightly modified example from JDK-8000423 was used:

import java.awt.Frame;
import java.awt.TextField;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import javax.swing.SwingUtilities;

public class DiacriticTest extends Frame {
    
    DiacriticTest() {
        
        super();
        addWindowListener(new WindowAdapter(){
            @Override
            public void windowClosing(WindowEvent e) { System.exit(0); }
            });
        setSize(300, 150);
        add(new TextField());
        setVisible(true);
    }

    public static void main(String[] args) {
        try {
            SwingUtilities.invokeAndWait(new Runnable() {
                @Override
                public void run() {
                    DiacriticTest t = new DiacriticTest();
                    t.setVisible(true);
                }
            });
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

When running this example on non-virtual machine (Ubuntu 12.04 linux, keyboard layout - 'English (US, alternative international)'), the result is as expected: diacritic signs can be displayed (using `+e, '+u etc.)

But when running the same test on the VirtualBox VM (the same Ubuntu), these symbols couldn't be displayed; at the same time these diacritics could be entered in other apps on VM (terminal, gedit, ...)

Moreover, if use 'English (US), international with dead keys' layout, diacritics could be added in the test application too.

The similar issue - cannot type Japanese (using IBus) when trying to run test for JDK-7146572 on VM but can type Japanese in other VM applications (terminal, editor).


Of course, I'm not totally sure if these issues are not resulting from some VM settings, but just in case...