Dll中如何改变mainform的Caption?(50分)

Dll中如何改变mainform的Caption?
我有时在dll中操纵MainForm的时候会出错，所以问一下如何访问，谢了[]

把MainForm作为一个var 变量,传入DLL 对应的FUNCTION OR PROCEDURE ,就可以任意
操纵MainForm. ;

我照你的话做了，可是还会出现那个地址错误的框框[]
能不能给一些源代码瞧瞧[]谢了

一个例子:
/////DLL
library Project1;
uses
; SysUtils, Classes,
; Unit1 in 'Unit1.pas';
{$R *.RES}
; exports Open;
begin
end.
//////////// Unit1
unit Unit1;

interface
; uses forms;
; procedure Open(var form :Tform);
implementation
; procedure Open(var form :Tform);
; begin
; ; form .Caption := 'abc';
; end;
end.
/////////////////
program Project2; 用它来调用dll
uses
; Forms,
; Unit2 in 'Unit2.pas' {Form2};

{$R *.RES}

begin
; Application.Initialize;
; Application.CreateForm(TForm2, Form2);
; Application.Run;
end.
//////////////////
unit Unit2;

interface

uses
; Windows, Messages, SysUtils, 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;
; procedure Open(var form :Tform);external 'Project1' ;
; implementation
{$R *.DFM}

procedure TForm2.Button1Click(Sender: TObject);
var
; form :TForm ;
begin
;form := Form2 as Tform;
;open(form);
end;

end.
//// 调试通过的!别忘给分啊

接受答案了.