sleep函数 会中止一些其它程序运行解决方法

sleep函数 会中止一些其它程序运行
在Delphi中调用sleep函数发现程序sleep了同时有部分windows的功能也被sleep了要到sleep完成。
比如新建一个程序
unit   Unit2;

interface

uses
    Windows,   Messages,   SysUtils,   Variants,   Classes,   Graphics,   Controls,   Forms,
    Dialogs,   StdCtrls;

type
    TForm2   =   class(TForm)
        Button1:   TButton;
        procedure   Button1Click(Sender:   TObject);
    private
        {   Private   declarations   }
    public
        {   Public   declarations   }
    end;

var
    Form2:   TForm2;

implementation

{$R   *.dfm}

procedure   TForm2.Button1Click(Sender:   TObject);
begin
    sleep(20000);//20秒
    //按下按钮后20秒内在windows的文件夹中双击word，Excel文档或.htm文件打不开
    //要到sleep完成
end;

end.
是为什么？
双击图片，.txt   等无影响

[解决办法]
MSDN中有解释的:

You have to be careful when using Sleep and code that directly or indirectly creates windows. If a thread creates any windows, it must process messages. Message broadcasts are sent to all windows in the system. If you have a thread that uses Sleep with infinite delay, the system will deadlock. Two examples of code that indirectly creates windows are DDE and COM CoInitialize. Therefore, if you have a thread that creates windows, use MsgWaitForMultipleObjects or MsgWaitForMultipleObjectsEx, rather than Sleep.