SWT GTK 64 bit and UBUNTU 11.04 NPE

Question

I'm currently working in an SWT standalone application. We usually work with windows but I'd like to work in Ubuntu.I set up the following environment.

Ubuntu 11.04 64bit Java 6 update 27 64 bit Eclipse Java EE 3.5 Galileo 64 bit I'm using SWT GTK 64 bit

I've got a few classes extending different SWT widgets.

For example

    public class MyCombo extends Combo implements CellEditor<Long> {
    private Set<ListenerRef> listeners = new HashSet<ListenerRef>();

@Override
    public void addListener(int eventType, Listener listener) {
        listeners.add(new MyCombo.ListenerRef(eventType, listener));
        super.addListener(eventType, listener);
    }

 @Override
    protected void checkSubclass() {
        // Do nothing
    }
.
.
.

This code works perfectly well in Windows 7 64 bit, running SWT32 bit and java32 bit, from eclipse 32 bit.

In Ubuntu 11.04 I get a NPE (NullPointerException) when trying to add a listener, it seems that the listeners set is null, but it shouldn't cause that set should be initialized as for the code above, and as I say it works in Windows 7

First I had problems running the SWT 32 bit app in Ubuntu64 bit cause there's seem to be a bug when running 32 apps in 64 ubuntu, so I tried to run it with the 64 version, and now I'm getting this error. If I avoid this NPE checking the set, I end up getting a

java.lang.NullPointerException
    at org.eclipse.swt.accessibility.Accessible.isValidThread(Unknown Source)
    at org.eclipse.swt.accessibility.Accessible.checkWidget(Unknown Source)
    at org.eclipse.swt.accessibility.Accessible.addRelation(Unknown Source)

Any ideas of what could be the reason? Are you aware of this problem in previous Ubuntu distrubutions? I don't get this problems in Windows 7, at least running SWT 32 bit

Please let me know if you need more details

Thanks and regards

BTW I forgot, SWT is 3.7 in Linux and 3.6.2 in Windows