DLL文件中Form的使用

贴出此文之前，未查阅过任何相似文章，如有相同，敬请见谅，并告示(注:本人曾就同一DLL中一窗体调用附窗体，如何实现之问题，请教过一前辈，但前辈笑笑未言)，此为我在写动态元件时想到的一方法，结果通过,各位见谅。我为初学，而求学路见艰难，贴出只望对象我一样初学者给点帮助，无他。
library DLLPJ;

uses
SysUtils,
Classes,
Unit1 in 'Unit1.pas' {Form1},
Unit2 in 'Unit2.pas' {Form2};

{$R *.res}

exports
ShowMainPRGWin;

begin
end.
----------
unit Unit1;

interface

uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Unit2,Dialogs, StdCtrls;
//1.附窗体单元加在此处
type
TForm1 = class(TForm)
Button1: TButton;
procedure Button1Click(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;

var
Form1: TForm1;
Form2: TForm2; //2.附窗体定义在此处
// Declare the export function of windows of the main DLL
function ShowMainPRGWin(AHandle:THandle):BOOL;StdCall;

implementation

{$R *.dfm}
function ShowMainPRGWin(AHandle:THandle):BOOL;
begin
Form1:=TForm1.Create(Application);
Form2:=TForm2.Create(Application); //3.创建附窗体
try
Form1.ShowModal;
Result:=False;
Finally
Form1.Free;
end;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
Form2.ShowModal;//4.在主窗体上调用附窗体
end;

end.
------------
unit Unit2;

interface

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

type
TForm2 = class(TForm)
private
{ Private declarations }
public
{ Public declarations }
end;

var
Form2: TForm2;

implementation

{$R *.dfm}

end.
----------
//在其他窗体上调用DLL的定义及方法
procedure ShowMainPRGWin(AHandle:THandle);StdCall External 'DLLPJ.DLL';

ShowMainPRGWin(1);