Well, if I understand how states works in OXC, it could be a problem. All event logic is processed after event popup window was opened. I'm not sure, but I think it is impossible with current solution to "suppress" event window popup if it fails it's game logic and should not be opened - even if we close it with code, it still will have some visible animations.
Because of that my initial solution was to put all event processing logic into event save game entity (like, say, alien missions work), not to state - its logic would decide, if we even need a state, or the event would be hidden.
Btw, this is not the only case - in my project I need some events to be processed with the game without noticing the player, like toggling some researches-triggers for campaign. Although, arc scripts could help, but they are processed monthly, thus not very agile to me.
Also, that would help with removing item from the base. Like something happened with alien artifact you found in UFO crash site if the player would not research it ASAP. Adding logic to interrupt the event if we don't have the required item in any of our bases before window popup would help to solve the problem.
Not like I'm arguing here to make some changes, as I can do that for my fork personally; just wanted to know what do you guys think about it, AFAIK some other modders would also like to have such feature.