Hidden and protected media functionality

There are three kinds of attributes any attachment can have:

• Attachment is Hidden
• Attachment is Hidden from listings and archives
• Attachment is in Protected folder

Hidden attachments can only be used:

• Inside article content
• As featured images

Hidden attachments will not be shown in:

• Galleries
• Content widgets, such as carousels
• Media Kit
• Homepage listings
• Archives
• Search
• Media Cart
• Attachment detail page

They will never automatically appear on homepage or in search. They cannot be discovered through search autosuggestion feature and it should not be possible to display them outside of article detail page.

The only exception is if Hidden attachment is set as a featured image of an article/post. In that case, this image will show up as a thumbnail wherever the article is visible (Homepage, Archives, search) but cannot be shown as a standalone image.

Such attachment cannot be downloaded through media cart or viewed as part of Media kit, galleries, carousels and such. If these attachments are added into media cart before they became Hidden, next visit of the media cart deletes these attachments from the user's selection.

Adding an attachment that is Hidden inside content widgets (such as galleries or carousels) and into Media kits will skip them until they are unhidden. Once they become unhidden, they will automatically show up in such places.

You can setup a date and time when the attachment becomes unhidden. This is essentially the same as opening the attachment at the given time and unchecking Hidden.

However, due to the nature of WordPress automatic scheduler, this time can vary from 0 to about 30 minutes after the specified time.

E.g. if you setup Hidden to UTC to 8:00 AM, the attachment can become unhidden any time between 8:00 AM and 8:30 AM with 99% of the attachments becoming unhidden in the first 10 minutes. Given the fact that Storyboard also uses a HTML caching mechanism that expires 30 minut