Throwing your hat

Does any one know the origin of the saying 'to throw one's hat/cap through the door?

I've seen that action in an old movie and took it as a test to see if the hat-owner is welcome to enter.

There is an old Irish custom of throwing your cap through the door to establish whether you're welcome or not: if not then it's thrown out immediately otherwise it's safe to go in, retrieve it and visit.

Another good reason to wear a hat.