private void fireTreeWillExpand (TreeExpansionEvent e, boolean expanded) throws ExpandVetoException {
    int size = weListeners.size();
    
    TreeWillExpandListener[] listeners = new TreeWillExpandListener[size];
    synchronized (this) {
        listeners = weListeners.toArray(listeners);
    }
    for (int i=0; i < listeners.length; i++) {
        if (expanded) {
            listeners[i].treeWillExpand(e);
        } else {
            listeners[i].treeWillCollapse(e);
        }
    }
}
 

private void fireTreeExpansionVetoed (TreeExpansionEvent e, ExpandVetoException ex) {
    int size = weListeners.size();
    
    TreeWillExpandListener[] listeners = new TreeWillExpandListener[size];
    synchronized (this) {
        listeners = weListeners.toArray(listeners);
    }
    for (int i=0; i < listeners.length; i++) {
        if (listeners[i] instanceof ExtTreeWillExpandListener) {
            ((ExtTreeWillExpandListener) listeners[i]).treeExpansionVetoed(e,
                ex);
        }
    }
}
 

/**
 * Maps {@code JTree.addTreeWillExpandListener(TreeWillExpandListener)}
 * through queue
 */
public void addTreeWillExpandListener(final TreeWillExpandListener treeWillExpandListener) {
    runMapping(new MapVoidAction("addTreeWillExpandListener") {
        @Override
        public void map() {
            ((JTree) getSource()).addTreeWillExpandListener(treeWillExpandListener);
        }
    });
}
 

/**
 * Maps
 * {@code JTree.removeTreeWillExpandListener(TreeWillExpandListener)}
 * through queue
 */
public void removeTreeWillExpandListener(final TreeWillExpandListener treeWillExpandListener) {
    runMapping(new MapVoidAction("removeTreeWillExpandListener") {
        @Override
        public void map() {
            ((JTree) getSource()).removeTreeWillExpandListener(treeWillExpandListener);
        }
    });
}
 

/**
 * A way to set a will expand listener, this was added as a hack to 
 * interface with the tree command.  This too will be nullified after
 * the footer has been called.
 * @param twel
 */
public void setTreeListeners(TreeWillExpandListener twel, 
        TreeSelectionListener tsl) {
    
    this.twel = twel;
    
    this.tsl = tsl;
}
 

/**
 * Add a TreeWillExpandListener.
 * @param l The tree will expand listener
 */
public synchronized void addTreeWillExpandListener (TreeWillExpandListener l) {
    weListeners.add(l);
}
 

/**
 * Remove a TreeWillExpandListener.
 * @param l The tree will expand listener
 */
public synchronized void removeTreeWillExpandListener (TreeWillExpandListener l) {
    weListeners.remove(l);
}