The load-time GL call scheduler that FEZ 1.12 uses

DrawActionScheduler.cs

using System;
using System.Collections.Concurrent;

namespace FezEngine.Tools
{
    public static class DrawActionScheduler
    {
        static readonly ConcurrentQueue<Action> DeferredDrawActions = new ConcurrentQueue<Action>();

        public static void Schedule(Action action)
        {
            if (!PersistentThreadPool.IsOnMainThread)
                DeferredDrawActions.Enqueue(action);
            else
                action();
        }

        public static void Process()
        {
            Action deferredAction;
            while (DeferredDrawActions.TryDequeue(out deferredAction))
                deferredAction();
        }
    }
}