How to add own GUI Status in Selection Screen – first you need to copy standard gui status from standard program, go to tcode SE90 and expand node Program Library -> Program SubObjects -> GUI Status. search GUI-Status %_00 in program RSSYSTDB.
Copy standard GUI-Status %_00 to Z Object to your Z Program.
And then you can modify your own GUI-Status on your selection screen.
Last, add this code on event INITIALIZATION to call your PF-Status for your selection screen
SET PF-STATUS 'ZPFSTATUS'.