New Filepicker can show additional information about files such as

datemodified
datecreated
size
author
license
icon (thumbnail with size 24x24)
image_width (in pixels, null if this is not an image)
image_height (in pixels, null if this is not an image)
realthumbnail (for lazy-loading, location of image preview)
realicon (for lazy-loading, location of image preview 16x16)

If external repositories provide such information our repository plugins must return it. For compatibility if 'datemodified' or 'datecreated' are not specified, the 'date' is used. But 'date', 'datemodified' and 'datecreated' must be UNIX timestamps.

Usually external repositories do not need to provide 'realthumbnail' and 'realicon' because 'thumbnail' and 'icon' are already image previews.

If repository does not return 'icon', the filetype icon from moodle set is used.

Repositories that need to be reviewed:

alfresco
boxnet
dropbox
flickr
flickr_public
googledocs
merlot
picasa
s3
url
webdav
wikimedia
youtube

Separate subtasks can be created for particular repositories

For existing attributes see http://docs.moodle.org/dev/Repository_plugins
Issue MDL-32600 to update documentation