I am working on a plugin that has a piece of meta data attached to each post. The fields are editable in a meta box on the post. This is all working fine.
I would like to prevent anyone from modifying the settings in meta box once the post has been published. By virtue of the application looking for this meta data, it doesn't make any sense for the meta data to change after publish.
So, is there any way to tell if a post has been published at least once? This way I can disable the controls in the meta box.