I made a list of all of the `XEVENTMGR.TriggerEvent calls I could find

EventToTrigger //Not an actual trigger, seems to be a generic event triggerer, no idea where the EventToTrigger variable gets set.

'OnSkyrangerArrives' //Pretty sure this triggers when you are about to launch the the mission, but you still have the option to 'return to avenger'

Can confirm as true - this event makes the "Begin Mission/Return to Avenger" buttons appear.

I believe (but I might be wrong) that it's used as a placeholder when the event to trigger is known, but will occur at an unknown time in the future. It's set when the event to trigger becomes known.

Otherwise, great work, thank you for looking into all these - I'll add it to my info compilation I'm working on.

I know right, there is not a lot of detail on how to use it right now yet though.

You can setup a callback to listen to a given event by using:

`XEVENTMGR.RegisterForEvent(ObjWithCallback, 'NameOfEvent', CallbackFunction, ELD_Immediate);

I've been using it mostly by creating a UIScreenListener and OnInit registering a trigger with a local function. So something along the lines of...

`XEVENTMGR.RegisterForEvent(SelfObj, 'UnitTakeEffectDamage', OnTakeDamage, ELD_Immediate);
...
function EventListenerReturn OnTakeDamage(Object EventData, Object EventSource, XComGameState GameState, Name EventID) {
    ...
    return ELR_NoInterrupt;
}

Honestly, I am not certain what the ELD/ELR enums are doing and haven't yet put time into finding them.

==EDIT==

I found the ELD/ELR enums in XComGameState.uc

enum EventListenerDeferral
{
	ELD_Immediate,		// The Listener will be notified in-line (no deferral)
	ELD_OnStateSubmitted,	// The Listener will be notified after the associated game state is processed
	ELD_OnVisualizationBlockCompleted,	// The Listener will be notified after the associated visualization block is completed
	ELD_PreStateSubmitted,	// The Listener will be notified immediately prior to the associated game state being added to the history
	ELD_OnVisualizationBlockStarted,	// The Listener will be notified when the associated visualization block begins execution
};

enum EventListenerReturn
{
	ELR_NoInterrupt,	// any subsequent event listeners WILL be processed; if ELD_Immediate, the event WILL NOT be interrupted
	ELR_InterruptEvent,	// any subsequent event listeners WILL be processed; if ELD_Immediate, the event WILL be interrupted
	ELR_InterruptListeners,	// any subsequent event listeners WILL NOT be processed; if ELD_Immediate, the event WILL NOT be interrupted
	ELR_InterruptEventAndListeners,	// any subsequent event listeners WILL NOT be processed; if ELD_Immediate, the event WILL be interrupted
};