When using group folders it happens to me regularly I want to remove from everyone the write permissions, e.g. that they can't accidentally break my documents.

What I'm doing at the moment:

1. I remove for every group with access to the group folder the "write" and "delete" permissions
2. I add for myself all permissions again

This has some obvious shortcomings:

1. If the admin give later additional groups access to the folder they are not covered and can edit my documents
2. If a lot of groups have access to the folder it is quite some work to remove the rights from each group

Proposed solution:

The "advanced permissions" drop-down has a virtual group called "all users". This way I can modify the access rights for everyone with one click.