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

[CuriousOne]

Here is the practical code I'm using, but it sometimes behaves strangely.
Say, button was pressed, action was made once, user still holds button, so no advance in code. But when user releases the button, sometimes it acts as button was pressed once again. Any ideas how to fix it?

MENULOOP: 'MAIN CONFIG SCREEN
IF UPBT=0 THEN
MENUITEM=MENUITEM+1
IF MENUITEM>4 THEN MENUITEM=1
GOSUB CENTRAL
pause 200 'debounce
ENDIF
WHILE UPBT=0:WEND 


IF DNBT=0 THEN
MENUITEM=MENUITEM-1
IF MENUITEM<1 THEN MENUITEM=4
GOSUB CENTRAL
pause 200 'debounce
ENDIF
WHILE DNBT=0:WEND
if menuitem=1 and rbut=0 then
pause 5
while rbut=0: wend
goto clockconfig
endif
GOTO MENULOOP