public virtual void visitOnGUI(){
if(_children!=null){
int count = _children.Count;
int i = 0;
for( ; i < count; i++ ) {
CCNode child = _children[i];
child.visitOnGUI();
}
drawOnGUI();
// draw children zOrder >= 0
for( ; i < count; i++ ) {
CCNode child = _children[i];
child.visitOnGUI();
}
}else
drawOnGUI();
}
protected virtual void drawOnGUI(){