如何使用Throttle过滤事件

我正在尝试一个双赢的反应框架。

IObservable<IEvent<MouseEventArgs>> mouseMoves = Observable.FromEvent<MouseEventArgs>(this, "MouseMove");
IObservable<IEvent<MouseEventArgs>> mouseDowns = Observable.FromEvent<MouseEventArgs>(this, "MouseDown");
IObservable<IEvent<MouseEventArgs>> mouseUps = Observable.FromEvent<MouseEventArgs>(this, "MouseUp");
var pointChanges = mouseMoves.Zip(mouseMoves.Skip(1), (prev, post) => new { Prev = prev, Post = post });
var mouseDrags = from d in mouseDowns
                 from p in pointChanges.TakeUntil(mouseUps)
                 select p;

我想过滤鼠标标记,只需要那些鼠标关闭后超过1秒的鼠标标记。怎么用?