How to use Word in TOleContainer in TForm properly, layout-wise?

Question

I wonder what is the suggested way to embed and control MS Word in a TForm, layout-wise? Currently, I (1) put two TPanel on TForm. The alBottom TPanel has one TButton, and the alClient TPanel has a alNone TOleContainer. (2) set up the layout in TMainForm.FormCreate event handler.

The problem is MS Word likes to take up all the space of its parent form. Only the fourth way as shown below seems to give acceptable layout. Based on trial-and-error, it seems necessary to use a sub-form instead of TPanel to host TOleContainer. (Also, Windows.SetParent seems necessary.) I wonder whether a sub-form is the correct way to go?

PS: Delphi XE, Word 2010, Windows 7

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sample code

unit uMainForm;

interface

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

type
  TMainForm = class(TForm)
    PanelOle: TPanel;
    PanelBtn: TPanel;
    OleContainer1: TOleContainer;
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
    procedure FormCreate(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  MainForm: TMainForm;

implementation

{$R *.dfm}

procedure TMainForm.FormCreate(Sender: TObject);
var
  OleForm: TForm;
begin
////
//// 1
////
//  OleContainer1.Parent := PanelOle;
//  OleContainer1.Align := alClient;
//
////
//// 2
////
//  Windows.SetParent(OleContainer1.Handle, PanelOle.Handle);
//  OleContainer1.Align := alClient;
//
////
//// 3
////
//  OleForm := TForm.Create(Self);
//  OleForm.Parent := PanelOle;
//  OleForm.Align := alClient;
//  OleForm.Visible := True;
//  OleContainer1.Parent := OleForm;
//  OleContainer1.Align := alClient;
//
////
//// 4 Works!
////
//  OleForm := TForm.Create(Self);
//  Windows.SetParent(OleForm.Handle, PanelOle.Handle);
//  OleForm.Align := alClient;
//  OleForm.Visible := True;
//  OleContainer1.Parent := OleForm;
//  OleContainer1.Align := alClient;
//
////
//// 5
////
//  OleForm := TForm.Create(Self);
//  OleForm.Parent := PanelOle;
//  OleForm.Align := alClient;
//  OleForm.Visible := True;
//  Windows.SetParent(OleContainer1.Handle,OleForm.Handle);
//  OleContainer1.Align := alClient;
//
////
//// 6
////
//  OleForm := TForm.Create(Self);
//  Windows.SetParent(OleForm.Handle, PanelOle.Handle);
//  OleForm.Align := alClient;
//  OleForm.Visible := True;
//  Windows.SetParent(OleContainer1.Handle,OleForm.Handle);
//  OleContainer1.Align := alClient;

end;

procedure TMainForm.Button1Click(Sender: TObject);
var
// Declare the item to be a generic OleVariant to force late binding
  Ds: OleVariant;
  D: OleVariant;
begin
  OleContainer1.CreateObjectFromFile('sample.docx', False);

  OleContainer1.Run;

  OleContainer1.AutoActivate := aaManual;
  OleContainer1.DoVerb(ovShow);  // not in FormCreate, in or after FormShow

  Ds := OleContainer1.OleObject.Application.Documents;
  Caption := IntToStr(Ds.Count);
end;

end.

Solution

Subform is a correct way to do it. We used this approach in a production environment and it worked. We hosted our "sub" form in a panel. However, we modified TOleContainer and TOleForm with a flag whether to use the parent form, or the topmost form:

procedure TOurOleContainer.InitObject;
...
begin
  if FDrawInTopForm then
    DocForm := GetParentForm(Self)
  else
    DocForm := TCustomForm(Parent);
...

Where FDrawInTopForm is a property we introduced. We also modified:

function GetVCLFrameForm(Form: TCustomForm; DrawInTopForm: Boolean): IVCLFrameForm;
begin
  if Form.OleFormObject = nil then TOleForm.Create(Form, DrawInTopForm); 
  Result := Form.OleFormObject as IVCLFrameForm;
end;

Unfortunately, due to agreements with the customer, I cannot post the complete solution here.