Vaadin Table Collapse Column Listener

I want to know which columns are collapsed & uncollapsed, in vaadin. Is there a listener for this, I could not found?

It's not supported out the box. However you could extends Table to support it.

Something like

public class ColumnCollapsedObservableTable extends Table {

    private List<ColumCollapsedListener> collapseListeners = new ArrayList<ColumCollapsedListener>();

    @Override
    public void setColumnCollapsed(Object propertyId, boolean collapsed)
            throws IllegalStateException {

        super.setColumnCollapsed(propertyId, collapsed);
        fireColumnCollapsedEvent(new ColumnCollapsedEvent(this, propertyId, collapsed));
    }

    public void addColumnCollapsedListener(ColumnCollapsedListener l) {
        ...
    }

    public void removeColumnCollapsedListener(ColumnCollapsedListener l) {
        ...
    }

    private fireColumnCollapsedEvent(ColumCollapsedEvent event) {
        ...
    }   

}