How to mask and unmask screen fields?

Question

Hi,
    I have a PNP LDB selection screen. Also I have an extra Key Date field at bottom ( apart from the std period selection ) , which is defined by me.If i enter some value in a particular field say, Action Type, I need to make my Key Date field an input field. But if the user does not enter any value in Action Type, then the Key Date field has to be grayed out. Right now what happens is , after i input something to Action Type, I need to press 'Enter' key to make the Key date active.
I am looping the screen in At sel screen o/p.  But , I dont want to press enter key. The moment i type something into Action type field, I need the other field to be active, just like the case of radiobuttons.Is ther any way out for this? Pls help....
Thanks in advance...
Mahesh

Answer 1

It's more that we're dealing with "block mode" communication from the GUI to the app server, so data only travels from the user to the program when some function is selected.
So there is a way if you were to set up your Action Type as a listbox (and assuming you are on a recent SAP release)... as per the example below.  This ties a user command into the change of a listbox setting - this example is for fun only of course, but if listbox1 is changed then the date opens, and if listbox2 is changed, it locks again.
Hope this helps.
Jonathan
report zlocal_jc_sdn_listbox_ucomm.
type-pools:
  vrm.
data:
  g_unlock             type sap_bool.
parameters:
  p_bukrs1             like t001-bukrs as listbox visible length 15
                         user-command zcc01,
  p_bukrs2             like t001-bukrs as listbox visible length 15
                         user-command zcc02,
  p_date               like sy-datum.
initialization.
  perform listbox_values_fill.
at selection-screen output.
  perform at_selection_screen_output.
at selection-screen.
  perform at_selection_screen.
start-of-selection.
  format reset.
  write: / 'Listbox 1 - you chose:', p_bukrs1.
  write: / 'Listbox 2 - you chose:', p_bukrs2.
*&      Form  at_selection_screen_output
form at_selection_screen_output.
* Toggle lock / unlock
  loop at screen.
    if screen-name = 'P_DATE'.
      if g_unlock is initial.
        screen-input = '0'.
      else.
        screen-input = '1'.
      endif.
      modify screen.
    endif.
  endloop.
endform.                    "at_selection_screen_output
*&      Form  at_selection_screen
form at_selection_screen.
  case sy-ucomm.
    when 'ZCC01'.  "CC 1 changed
      g_unlock = 'X'.
    when 'ZCC02'.  "CC 2 changed
      g_unlock = ' '.
  endcase.
endform.                    "at_selection_screen
*&      Form  listbox_values_fill
form listbox_values_fill.
  data:
    l_id                type vrm_id,
    lt_value            type vrm_values,
    l_value             like line of lt_value.
* Listbox 1:
  l_id = 'P_BUKRS1'. "name of variable in screen
  l_value-key = '1000'.
  l_value-text = 'London'.
  append l_value to lt_value.
  l_value-key = '2000'.
  l_value-text = 'New York'.
  append l_value to lt_value.
  l_value-key = '3000'.
  l_value-text = 'Canberra'.
  append l_value to lt_value.
  call function 'VRM_SET_VALUES'
    exporting
      id     = l_id
      values = lt_value.
* And re-use the list for listbox 2
  l_id = 'P_BUKRS2'. "name of variable in screen
  call function 'VRM_SET_VALUES'
    exporting
      id     = l_id
      values = lt_value.
endform.                    "listbox_values_fill