Telling if an object is a container...

PROCEDURE cont_check
PARAMETER cobject
DO CASE
CASE PEMSTATUS(&cobject.,"Controls",5) ;
OR PEMSTATUS(&cobject.,"Buttons",5) ;
OR PEMSTATUS(&cobject.,"Pages",5) ;
OR PEMSTATUS(&cobject.,"Columns",5)
RETURN .T.
OTHERWISE
RETURN .F.
ENDCASE
EndProc

Of course what you check with pemstatus() is up to you...