In the _Ready() override I put
AddSeparator();
SetItemId(0, 99);
AddItem("option 1", id:0);
AddItem("option 2", id:1);
AddItem("option 3", id:2);
AddItem("option 4", id:3);
AddItem("option 5", id:4);
But it is still returning the actual index instead of the assigned Id's when the menu options are clicked, with the seperator at 0 and the actual menu items id's are still returned as 12345 instead of 01234. Is there a way to alter the seperator's ID?