Why doesn't WINWORD.EXE quit after Closing the document from Delphi? - delphi

Question

I managed to distill one of the underlying issues rooted in my question How to trace _AddRef / _Release calls for OLE Automation objects in the unit below.
I'll answer this answer too, just in case anyone else bumps into this.
The question: with the below code, why doesn't WINWORD.EXE always quit (sometimes it does quit).
The unit can probably be trimmed down even more.
unit Unit2;
interface
uses
Winapi.Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls,
Forms, Dialogs, StdCtrls,
WordXP;
type
TForm2 = class(TForm)
WordXPFailsToQuitButton: TButton;
procedure WordXPFailsToQuitButtonClick(Sender: TObject);
private
FWordApplication: TWordApplication;
strict protected
function GetWordApplication: TWordApplication; virtual;
function GetWordApplication_Documents: Documents; virtual;
procedure WordApplication_DocumentBeforeClose(ASender: TObject; const Doc: _Document; var Cancel: WordBool); virtual;
procedure WordApplication_Quit(Sender: TObject); virtual;
property WordApplication: TWordApplication read GetWordApplication;
property WordApplication_Documents: Documents read GetWordApplication_Documents;
end;
var
Form2: TForm2;
implementation
uses
Vcl.OleServer;
{$R *.dfm}
function TForm2.GetWordApplication: TWordApplication;
begin
if not Assigned(FWordApplication) then
begin
FWordApplication := TWordApplication.Create(nil);
FWordApplication.AutoConnect := False;
FWordApplication.AutoQuit := False;
FWordApplication.ConnectKind := ckNewInstance;
FWordApplication.OnDocumentBeforeClose := WordApplication_DocumentBeforeClose;
FWordApplication.OnQuit := WordApplication_Quit;
FWordApplication.Connect;
end;
Result := FWordApplication;
end;
function TForm2.GetWordApplication_Documents: Documents;
begin
Result := WordApplication.Documents;
if not Assigned(Result) then
raise EAccessViolation.Create('WordApplication.Documents');
end;
procedure TForm2.WordXPFailsToQuitButtonClick(Sender: TObject);
begin
try
WordApplication_Documents.Add(EmptyParam, EmptyParam, EmptyParam, EmptyParam);
WordApplication.Visible := True;
WordApplication.ActiveDocument.Close(False, EmptyParam, EmptyParam);
finally
WordApplication.OnQuit := nil;
WordApplication.OnDocumentBeforeClose := nil;
WordApplication.AutoQuit := True;
WordApplication.Disconnect;
WordApplication.Free;
FWordApplication := nil;
end;
end;
procedure TForm2.WordApplication_DocumentBeforeClose(ASender: TObject; const Doc: _Document; var Cancel: WordBool);
begin
FWordApplication.Disconnect;
end;
procedure TForm2.WordApplication_Quit(Sender: TObject);
begin
FWordApplication.Disconnect;
end;
end.

Answer 1

Answer part 1:
Comment out the disconnect in the below event:
procedure TForm2.WordApplication_DocumentBeforeClose(ASender: TObject; const Doc: _Document; var Cancel: WordBool);
begin
// FWordApplication.Disconnect;
end;
The event will be called during the DocumentClose(...) method, then disconnect and delete the OLE interface from the FWordApplication instance.
I have not yet figured out which reference is dangling, but this effectively keeps WINWORD.EXE alive most of the times.
Answer part 2:
Sometimes WINWORD.EXE does quit because toe WordApplication_DocumentBeforeClose event is not called. The reason is that the code runs so fast that Word is not fully initialized yet to perform the event.