protected void setNodeExpanded(TreePath keyPath, boolean expanded) {
boolean oldExpansion = isNodeExpanded(keyPath);
if (expanded == oldExpansion) return;
expansionState = expansionState.getMutableExpansionState();
expansionState.setNodeExpanded(keyPath, expanded);
}
protected boolean isNodeExpanded(TreePath keyPath) {
if (keyPath == null) return false;
return expansionState.isNodeExpanded(keyPath);
}
