How to center the oracle forms 10g (windows)

when-new-forms-instance----------------------------------

Declare
       
  v_window      varchar2(100):='WINDOW1';
    v_width                number(4);
    v_height            number(4);
    vw                        number(4);
    vh                        number(4);
   
BEGIN
    SET_WINDOW_PROPERTY(FORMS_MDI_WINDOW,WINDOW_STATE,MAXIMIZE);
  SET_WINDOW_PROPERTY('WINDOW1',WINDOW_STATE,MAXIMIZE);
    set_window_property(forms_mdi_window,title,'STAR CERAMICS LIMITED                                    HUMAN RESOURCE MANAGEMENT SYSTEM (HRMS)');
    vw:=gET_application_PROPERTY(DISPLAY_WIDTH)-50;
    vh :=gET_application_PROPERTY(DISPLAY_HEIGHT)-180;

    v_width := Get_Window_Property(v_WINDOW, WIDTH);
    v_height:= Get_Window_Property(v_WINDOW, HEIGHT);

  Set_Window_Property(v_WINDOW, POSITION, (vw-v_width)/2, (vh-v_height)/2) ;
 
      replace_menu(:global.path||'HRM10g\Attendance\Forms\atten_menu.mmx');
END;



exit btn
------------
replace_menu();
exit_form(no_validate);