on_o = show_debug(); is wrong.. you have to assign the function pointer!: on_o = show_debug;

The reason is that the on_ events are function* pointer callbacks which are automatically executed. If you would like to assign several function depending on the gamestate, use a wrapper function which does the selection:

Code:

---

function on_o_event ()
{
   if (gameState == gs_mainMenu) {
      switchDebugMenu();   
   } else {
      switchDebugDefault();
   }
}

on_o = on_o_event;

---

Or something like this..