Using same button for entering/exiting some part of code?

[HenrikOlsson]

There does not seem to be any debounce on button release. Try

  IF UPBT=0 THEN
    MENUITEM = MENUITEM+1

    IF MENUITEM > 4 THEN MENUITEM = 1
    GOSUB CENTRAL 
    ' PAUSE 20          ' May be needed if subroutine CENTRAL executes very fast.
    WHILE UPBT = 0 : WEND
    PAUSE 20 'debounce
  ENDIF