Creating ToolBar buttons in containers Using CL_GUI_TOOLBAR class

Class - CL_GUI_TOOLBAR provides methods to create toll bar buttons ( of different types) on the container.
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DATA : lr_toolbar TYPE REF TO cl_gui_toolbar,
lr_cust_cont TYPE REF TO cl_gui_custom_container.

CALL SCREEN 0001.
*&---------------------------------------------------------------------*
*&      Module  CREATE_PFSTATUS  OUTPUT
*&---------------------------------------------------------------------*
MODULE create_pfstatus OUTPUT.
  SET PF-STATUS 'STATUS'.
ENDMODULE.                 " CREATE_PFSTATUS  OUTPUT
*&---------------------------------------------------------------------*
*&      Module  CREATE_TOOLBAR  OUTPUT
*&---------------------------------------------------------------------*
MODULE create_toolbar OUTPUT.
  IF lr_cust_cont IS NOT BOUND.
    CREATE OBJECT lr_cust_cont
      EXPORTING
        container_name = 'TOOLBAR'
        repid          = sy-repid
        dynnr          = sy-dynnr.

  ENDIF.

  IF lr_toolbar IS NOT BOUND.
    CREATE OBJECT lr_toolbar
      EXPORTING
        parent             = lr_cust_cont
        display_mode       = cl_gui_toolbar=>m_mode_horizontal
        name               = 'Demo Toolbar'
      EXCEPTIONS
        cntl_install_error = 1
        cntl_error         = 2
        cntb_wrong_version = 3
        OTHERS             = 4.

  ENDIF.

  CALL METHOD lr_toolbar->add_button
    EXPORTING
      fcode            = 'TSAVE'  " Function Code of Button
      icon             = '@2L@'    " Icon Name
*     is_disabled      =     " Button Status
      butn_type        = 0   " Button Types Defined in CNTB
      text             = 'Save'  " Text Shown to the Right of the Image
      quickinfo        = 'Click to update the database'
*     is_checked       =     " Button Selected
    EXCEPTIONS
      cntl_error       = 1
      cntb_btype_error = 2
      cntb_error_fcode = 3
      OTHERS           = 4.

ENDMODULE.                 " CREATE_TOOLBAR  OUTPUT
*&---------------------------------------------------------------------*
*&      Module  HANDLE_USERACTION  INPUT
*&---------------------------------------------------------------------*
module HANDLE_USERACTION input.
CASE sy-ucomm.
  WHEN 'BACK' OR 'EXIT' OR 'CANCEL'.
    LEAVE TO SCREEN 0.
  WHEN OTHERS.
ENDCASE.
endmodule.                 " HANDLE_USERACTION  INPUT

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Domain fixed value defines Button Types.