Setting the GUI Status for a Selection-Screen

In dialog programming, you may already be familiar with the setting of the PF-STATUS (known as the GUI Status) prior to calling a screen.  Usually, the code looks something like this:

set pf-status ‘STATUS_2000’.
call screen ‘2000’.

I recently discovered that this does not work at all when calling a selection screen.
Here was my non-working code:

set pf-status ‘STATUS_2100’.
call selection-screen ‘2100’.

Even if you walk through the code using the debugger, the statement appears to execute, but the GUI status that is presented when selection-screen 2100 is called is the GUI status that was already running prior to calling the new selection-screen.  So, when the new selection-screen is called, the application buttons do not match the new selection-screen.

The solution, I discovered, is that you need to call SAP function module RS_SET_SELSCREEN_STATUS, and it needs to be called in the selection-screen output event.  Here is my working code:

at selection-screen output.
case sy-dynnr.
when ‘2100’.
call function ‘RS_SET_SELSCREEN_STATUS’
EXPORTING
P_STATUS  = ‘STATUS_2100’
TABLES
P_EXCLUDE = exclude.

when ‘2200’.
call function ‘RS_SET_SELSCREEN_STATUS’
EXPORTING
P_STATUS  = ‘STATUS_2200’
TABLES
P_EXCLUDE = exclude.

endcase.

So now, when a selecion-screen is called (as in CALL SELECTION-SCREEN ‘2100’.), the PBO event
for that selection-screen will take us to the AT SELECTION-SCREEN OUTPUT  event code,
and will set the GUI status properly.