Make a folder read-write for all users without using ACLs

People often want to share a folder on their startup drive (or another drive with ownership enabled) between several local users. It's easy to change permissions on the whole folder, but any newly created files inside that folder will only be writable by the user that created them.

A standard way of dealing with this issue is by using inherited ACLs as described in this hint. However, that method has a couple of drawbacks. Namely, some applications like Open Office don't understand ACLs. Other applications use temporary files when saving files that can wash out the ACLs, depending on particular setup. That includes, for example, Photoshop which strips off ACLs on re-saves. Lastly, inherited ACLs are only applied to newly created files and files copied to the shared folder. They are not applied to files moved to the shared folder. The proposed method of sharing a folder has no such deficie...