erty OnMouseUp;
    property OnStartDock;
    property OnStartDrag;
  end;

procedure Register;

implementation

procedure TCustomREdit.CreateParams(var Params: TCreateParams);
const
  Alignments: array[Boolean, TAlignment] of DWORD =
    ((ES_LEFT, ES_RIGHT, ES_CENTER),(ES_RIGHT, ES_LEFT, ES_CENTER));
begin
  inherited CreateParams(Params);
  with Params do
  begin
    Style := Style or Alignments[UseRightToLeftAlignment, FAlignment];
  end;
end;

procedure TCustomRedit.SetAlignment(Value:TAlignment);
begin
  if FAlignment <> Value then
  begin
    FAlignment := Value;
    RecreateWnd;
  end;
end;

procedure Register;
begin
  RegisterComponents(''Samples'', [TREdit]);
end;

end.

上述只是给初学Delphi控件制作者一点参考，当然不入方家法眼。不足之处，敬请指正。