为什么老出错误，请大哥指教！

Question

unit Unit1;interface uses
Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls;type 
TForm1 = class(TForm) 
Button1: TButton; 
Button2: TButton;
procedure Button1Click(Sender: TObject); 
procedure FormCreate(Sender: TObject); 
private
{ Private declarations }
public{ Public declarations } 
end;var
Form1: TForm1;implementation{$R *.dfm}
function MyThreadFunc(P:pointer):Longint;stdcall;
var
i:integer;
DC:HDC;
S:string;
begin
DC:=GetDC(Form1.Handle);
for i:=0 to 100000 do begin
S:=Inttostr(i);
Textout(DC,10,10,Pchar(S),length(S));
end;
ReleaseDC(Form1.Handle,DC);
end;procedure TForm1.FormCreate(Sender: TObject);
begin
MyThreadfunc(nil);
end;procedure TForm1.Button1Click(Sender: TObject);
var
hThread:Thandle;//定义一个句柄
ThreadID:DWord;
begin
//创建线程，同时线程函数被调用
hthread:=CreateThread(nil,0,@MyThreadfunc,nil,0,ThreadID);
if hThread=0 then
messagebox(Handle,'Didn’t Create a Thread',nil,MB_OK);
end;end.