I do not tell a current employer I'm looking for work and I put that they cannot contact my current employer.
I can't have a possible job oppurtunity compromise the job I actually have. And there is no telling how long after I fill out this application that they will still be able to pull it up and check it out.

Also if they think that is unreasonable, that I don't want them contacting the employer I have now. I probably don't want to work for them.