{$IFDEF in_interface}
type
  IObject = interface
    ['{A6A98F7F-B435-478C-BA80-8259A1473450}']
    // FIXME different GUID depending on OS?   
    function GetHandle : TExternalHandle;
    property Handle : TExternalHandle read GetHandle;
  end;

  TObject = class(TInterfacedObject, IObject, IInterface)
  protected
    fHandle : TExternalHandle;
    fBOwnsHandle : TBoolean;
  private
    fMessageMap : TMessageMap;
  protected
    function GetHandle : TExternalHandle;
  protected
    procedure DeleteUnderlyingObject; virtual; abstract;
    procedure InitMessageMap(var aMessageMap : TMessageMap); virtual;
  public
    destructor Destroy; override;
  published
    { when creating, call this as:
        inherited Reuse(CheckError(Windows.CreateWindow(...)), True);
    }
{$IFDEF X11}
  private
    fDisplay : PDisplay;
  public
    property Display : PDisplay read fDisplay;
  published
    constructor Reuse(aDisplay : PDisplay; aHandle : TExternalHandle; aBOwnsHandle : TBoolean);
{$ELSE}
    constructor Reuse(aHandle : TExternalHandle; aBOwnsHandle : TBoolean);
{$ENDIF}
    property Handle : TExternalHandle read GetHandle;
  end;

{$ENDIF}
{$IFDEF in_implementation}

{$IFDEF X11}
constructor TObject.Reuse(aDisplay : PDisplay; aHandle : TExternalHandle; aBOwnsHandle : TBoolean);
begin
  fDisplay := aDisplay;
  fHandle := aHandle;
  fBOwnsHandle := aBOwnsHandle;
end;
{$ELSE}
constructor TObject.Reuse(aHandle : TExternalHandle; aBOwnsHandle : TBoolean);
begin
  fHandle := aHandle;
  fBOwnsHandle := aBOwnsHandle;
  InitMessageMap(fMessageMap);
end;

{$ENDIF}

procedure TObject.InitMessageMap(var aMessageMap : TMessageMap);
begin
end;

destructor TObject.Destroy;
begin
  if (fBOwnsHandle) then
    DeleteUnderlyingObject;

  inherited Destroy;
end;

function TObject.GetHandle : TExternalHandle;
begin
  Result := fHandle;
end;

{$ENDIF}