Possible Duplicates:
You should be able to vote to reopen a question before it is actually closed.
How about a “Vote not to close” option to counter the “Vote to close”?

It would be nice if people could vote against a running close-vote. I.e. to vote for keeping it open while others vote for close it.

And then the question only gets closed if the difference between both votes, i.e. close votes - keep-open votes >= 5.

Or why is it not made already like that?

Question which are closed at some points are very unlikely to be reopened because not much people will see the question anymore. Only the people who have been involved in discussions on that question may recheck it later and that are likely to less to reopen it. So arguing that a closed question can just be reopened is not a valid argument I think.