Hi Nadya,
Just returning a favor :)

< SNIP >
>If, however, for this particular user or this particular regime the button never would be accessible, I would make it invisible.

The word 'regime' has followin definitions neither of wich is what you want.

1. A form of government: a fascist regime. b. A government in power; administration: suffered under the new regime.
2. A prevailing social system or pattern.
3. The period during which a particular administration or system prevails.
4. A regulated system, as of diet and exercise; a regimen.

I think word 'mode' would be appropriate here,