OrderingList removing elements (firefox only, IE works fine)

[shikida]

This is probably one of those very rare cases where something works in IE 8.0.6001 and not in FF 3.6.8

I have an OrderingList, scope request+keepAlive. My converter is

/* (non-Javadoc)
     * @see javax.faces.convert.Converter#getAsObject(javax.faces.context.FacesContext, javax.faces.component.UIComponent, java.lang.String)
     */
    @Override
    public Object getAsObject(FacesContext arg0, UIComponent arg1, String arg2) {
        String id = arg2.substring(0, arg2.indexOf('_'));
        String desc = arg2.substring(arg2.indexOf('_')+1, arg2.length());
        PerguntaHelper ph = new PerguntaHelper();
        ph.setCoSeqPergunta(Integer.valueOf(id));
        ph.setDsPergunta(desc);
        return ph;

    }

    /* (non-Javadoc)
     * @see javax.faces.convert.Converter#getAsString(javax.faces.context.FacesContext, javax.faces.component.UIComponent, java.lang.Object)
     */
    @Override
    public String getAsString(FacesContext arg0, UIComponent arg1, Object arg2) {  
        PerguntaHelper ph = (PerguntaHelper) arg2;
        return ph.getCoSeqPergunta()+"_"+ph.getDsPergunta();
    }

My object implements hashcode and equals

public class PerguntaHelper implements Serializable{

    private static final long serialVersionUID = -2103294699705607573L;
    private Integer coSeqPergunta;
    private String dsPergunta;
   
    public PerguntaHelper(){
       
    }

    @Override
    public int hashCode() {
        return this.getCoSeqPergunta().hashCode();
    }

    @Override
    public boolean equals(Object obj) {
        return this.getCoSeqPergunta().equals(((PerguntaHelper) obj).getCoSeqPergunta());
    }

(...)

  
}

now, watch the behaviour.

My orderingList

item 1

item 2

item 3

then I select item 2 and move it up

item 2

item 1

item 3

then before I save the list, item 1 has vanished

saving item 2

saving item 3

the screen is re-rendered (new request, the method returns a string)

item 2

item 3

then I select item 2 and move it down

item 3

item 2

then before I save the list, item 3 has vanished

saving item 2

finally, the screen is re-rendered, showing just item 2

I am using RF 3.3.3

TIA

Leo K.