Small tip: If you have a folder in your mesh that someone else shared to you before the permissions were updated to allow “read only” permissions, you are still an “owner” on the folder.
Today I was copying a 1.2GB folder around and accidentally dropped it onto someone else’s folder which I need read access to but I don't contribute to. After a minute I realized the problem and deleted the folder, but the news feed shows that I was an idiot and announced it to everyone on the folder.
Luckily this wasn’t personal data! Also, being an owner of the folder, I was able to manage the member’s list and kick myself off so now I’m just a reader.