I have an app that downloads ZIP files from my server, and can download plugins from other servers. Before being able to open these files, I would like to present one of the classic '"Filename.html" is a (file type) downloaded from the internet. Are you sure you want to open it?" messages when first attempting to open the file, much like Google Chrome does when you save a HTML file and attempt to open it:
I've read that this is enabled by setting a special file attribute, but I'm not entirely sure what attribute it is, and how to set it on these files.
File Quarantine is documented here