0
OnClick = Button1Click
end
end

完整的代码如下：

unit Use_Unit;

interface

uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls;
type
TForm1 = class(TForm)
Button1: TButton;
procedure Button1Click(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;

var
Form1: TForm1;
procedure LoadForm; external ''usedll.dll'' index 1;
implementation

{$R *.dfm}

procedure TForm1.Button1Click(Sender: TObject);
begin
LoadForm;
end;

end.


三、MDI-Child在DLL中载入并使用
    如果是MDI-Child又如何在DLL中载入并使用呢，下面就这个问题说说使用DLL文件中封装的窗口。
新建一个DLL工程，保存为mdidll，再新建一个窗体，FormStyle设为fsMDIChild，如下：
object Form1: TForm1
Left = 192
Top = 133
Width = 344
Height = 234
Caption = ''MDI''
Color = clBtnFace
Font.Charset = DEFAULT_CHARSET
Font.Color = clWindowText
Font.Height = -11
Font.Name = ''MS Sans Serif''
Font.Style =
FormStyle = fsMDIChild
OldCreateOrder = False
Position = poDefault
Visible = True
OnClose = FormClose
PixelsPerInch = 96
TextHeight = 13
end

代码如下：

unit mdi_Unit;

interface

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

type
TForm1 = class(TForm)
procedure FormClose(Sender: TObject; var Action: TCloseAction);
private
{ Private declarations }
public
{ Public declarations }
MyParentForm: TForm;
MyParentApplication: TApplication;
end;

var
DllApplication: TApplication;
implementation

{$R *.dfm}

procedure TForm1.FormClose(Sender: TObject; var Action: TCloseAction);
begin
Action:=caFree;
end;

end.





library mdidll;

uses
Windows,
Messages,
SysUtils,
Classes,
Graphics,
Controls,
Forms,
Dialogs,
mdi_Unit in ''mdi_Unit.pas'' {Form1};

procedure LoadChild(ParentApplication: TApplication; ParentForm: TForm); export; stdcall;
var
Form1: TForm1;
DllProc: Pointer;

begin
Application:=ParentApplication;
Form1:=TForm1.Create(ParentForm);
Form1.MyParentForm:=ParentForm;
Form1.MyParentApplication:=ParentApplication;
Form1.Show;
end;

procedure DLLUnloadProc(Reason: Integer); register;
begin
if Reason = DLL_PROCESS_DETACH then Application:=DllApplication;
end;

{$R *.res}
exports
LoadChild;
begin
DllApplication:=Application;
DLLProc := @DLLUnloadProc;
end.


编译后生成mdidll.dll文件。
使用DLL中的MDI-Child窗口如下：

    新建一个工程，主窗口设置如下FormStyle设为fsMDIForm：
object Form1: TForm1
Left = 192
Top = 133
Width = 544
Height = 375
Caption = ''Form1''
Color = clBtnFace
Font.Charset = DEFAULT_CHARSET
Font.Color = clWindowText
Font.Height = -11
Font.Name = ''MS Sans Serif''
Font.Style =
FormStyle = fsMDIForm
Menu = MainMenu1
OldCreateOrder = False
PixelsPerInch = 96
TextHeight = 13
object MainMenu1: TMainMenu
Left = 72
Top = 136
object N1: TMenuItem
Caption = #26032#24314''(&N)''
OnClick = N1Click
end
end
end
代码：

unit usemdi_Unit;

interface

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

type
TForm1 = class(TForm)
MainMenu1: TMainMenu;
N1: TMenuItem;
procedure N1Click(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;
T_ProvaChild = proc