REPEAT
  ALERT 2," | Umschalten | auf 50 Hertz",1," Ok ",button|
  '
  GOSUB gfa_sw5060__(50)
  '
  ALERT 2," | Umschalten | auf 60 Hertz",1," Ok ",button|
  '
  GOSUB gfa_sw5060__(60)
  '
  ALERT 2," | Nochmal | ",1," Ja |Nein",button|
UNTIL button|=2