DestroyAllChildren function called from MenuScreen does not actually destroys MenuScreen's Items; at least Numtems is not set to 0.

For 1.23.1 - It seems that this method now destroys only those children (Items) that were created automatically (e.g. menu Title object). It does not move object references that are left to the beginning of Items array though (hence ItemsNum value stays unchanged), leaving null references there. Is this is how it was supposed to be?

Yes.