Hi!
When is it too late to cancel an event? 
I'm passing an event reference to a helper class and then trying to reference it in a different method (within a GUI class) but after getting a reference to the event and then calling setCancelled(true) on it the event is not cancelled.
Hope that makes sense 
Depends on what you are doing exactly, e.g. if you are waiting for player input before cancelling the event then that it done via a callback so you can't be sure it will be executed before the player has actually finished doing whatever they were doing to trigger the event.
ok I thought so, unfortunately something like this is impossible to achieve with a callback. Which event exactly are you using? maybe we can find a way around it.
The way I would go about doing something like this is to cancel the event then open the GUI to wait for the answer and then do what the event was supposed to do with my own method manually. But that depends on which event you are using and if the API currently permits doing the wanted process manually.
The way I would go about doing something like this is to cancel the event then open the GUI to wait for the answer and then do what the event was supposed to do with my own method manually
You sir are a genius! That would work! 
Yes I'm working with inventories so there is defiantly API functions there! I was about to throw the towel in for the day and go play Kingdom Come but this has given me fresh inspiration!
Many thanks
I'm glad to hear this issue is solved 
In general, it's important to cancel an event in the same frame / tick, so basically the event instance is "worthless" in the next frame (so it cannot be used in a callback [which is always called a few ticks later - depending on how long it takes to get the response from the client] or in another thread). So the approach mentioned by @Minotorious would be the proper way to solve this 
Yep I used Mino's approach and I got it working in no time at all. 
