Treetable DoubleClick

We use a TreeTable.

In conjunction with a
double-click
it works
only
when the TreeTabel previously
selected
.



  treetable.addListener(new ItemClickEvent.ItemClickListener() {
            @Override
            public void itemClick(ItemClickEvent event) {
                if (event != null) {
                                    
                    if (event.isDoubleClick()) {
                      [b]
open a window here....
[/b]
                      etc...

If the double click to run
directly
on the table throws java a null pointer exception.
Maybe someone knows a solution for this?

Thanks in advance