gzdoom-gles/wadsrc/static/zscript/events.txt

class StaticEventHandler : Object native
{
    // static event handlers CAN register other static event handlers.
    // unlike EventHandler.Create that will not create them.
    protected static native StaticEventHandler Create(class<StaticEventHandler> type);
    protected static native StaticEventHandler CreateOnce(class<StaticEventHandler> type);
    protected static native StaticEventHandler Find(Class<StaticEventHandler> type); // just for convenience. who knows.
    
    protected static native bool Register(StaticEventHandler handler);
    protected static native bool Unregister(StaticEventHandler handler);

    // world stuff
    virtual void WorldLoaded() {}
    virtual void WorldUnloaded() {}
    virtual void WorldThingSpawned() {}
    // render stuff
    virtual void RenderFrame() {}
}

class StaticRenderEventHandler : StaticEventHandler native
{
    // for frame and camera
    native readonly Vector3 ViewPos;
    native readonly double ViewAngle;
    native readonly double ViewPitch;
    native readonly double ViewRoll;
    native readonly double FracTic;
    native readonly Actor Camera;
}

class StaticWorldEventHandler : StaticEventHandler native
{
    // for world
    native readonly bool IsSaveGame; // this is set to true if static WorldLoaded was triggered during savegame loading.
    native readonly Actor Thing; // this is for WorldThingSpawned
}

class EventHandler : StaticEventHandler native
{
    static native StaticEventHandler Create(class<StaticEventHandler> type);
    static native StaticEventHandler CreateOnce(class<StaticEventHandler> type);
    static native StaticEventHandler Find(class<StaticEventHandler> type);

    static native bool Register(StaticEventHandler handler);
    static native bool Unregister(StaticEventHandler handler);
}

class RenderEventHandler : StaticRenderEventHandler native { }