Hello people... What happens when I score a agenda with 3 more agendas in the hand, 3 gang sign in the ring and a Strongbox rezzed in hq with the runner don't having more clicks? Thanks.

No clicks, no steal.

Strongbox isn't limited to just during a run.

Nungunz is right, however it's worth going into slightly more detail.

1. The runner can access agendas from HQ but since he or she does not have clicks on the corp's turn, the additional cost cannot be paid.

2. If Maw is installed, it might trash an Agenda from HQ.

3. Gang Sign is often used in conjunction with HQ interface, which triggers with each Gang Sign access. So with 6 accesses the runner will very likely Trash any other cards in HQ which can be, and will probably end with perfect knowledge of what remaining cards are in HQ.

So, while I would much rather have the Strongbox protecting my agendas in this scenario than not, it's far from a sure thing and the information revealed is still going to be a huge setback to the corp.