public void popSequence() {
   if (stack == null) {
     return;
   }
   if (stack.size() == 0) {
     System.err.println("Stack underflow " + this + "/" + getAnimation());
     return;
   }
   StackEntry se = stack.pop();
   setAnimationNoRewind(se.animation);
   setSequence(se.sequence);
 }