选择Screen增添操作按钮

不管是做比较繁琐的屏幕绘制还是简单的ALV报表，有时特殊要求还是需要我们对选择屏幕添加一些按钮。
简单的汇总一下：
1. 定义所需类和字段：
    TYPE-POOLS icon.
    TABLES sscrfields.
    DATA:functxt TYPE smp_dyntxt.
2. 选择界面定义：
    SELECTION-SCREEN: FUNCTION KEY 1.
3.初始化字段
   INITIALIZATION.
      functxt-icon_id = icon_compare.
      functxt-icon_text = '跳转至新程序'.
      sscrfields-functxt_01 = functxt.
4.AT SELECTION-SCREEN.里面控制按钮相应
    DATA: lr_screen TYPE TABLE OF rsparams,
             ls_screen LIKE LINE OF lr_screen.
    CLEAR ls_screen.
    ls_screen-selname = 'S_BUKRS'.
    ls_screen-kind    = 'S'.
    ls_screen-sign    = 'I'.
    ls_screen-option  = 'EQ'.
    ls_screen-low     = s_bukrs-low.
    APPEND ls_screen TO lr_screen.

    CLEAR ls_screen.
    ls_screen-selname = 'S_VKORG'.
    ls_screen-kind    = 'S'.
    ls_screen-sign    = 'I'.
    ls_screen-option  = 'EQ'.
    ls_screen-low     = s_vkorg-low.
    APPEND ls_screen TO lr_screen.

    CASE sscrfields-ucomm.
        WHEN 'FC01'.
           SUBMIT ZSDR002_NEW VIA SELECTION-SCREEN WITH SELECTION-TABLE lr_screen AND RETURN.
        WHEN OTHERS.
    ENDCASE.