I am using Attachments 184.108.40.206 on WordPress 3.5.2.
If I configure a custom Attachments instance with
'filetype' => array('image'), it seems that the filetype restriction is only applied when selecting item from media library (it correctly shows only images) but not when uploading a new file using the media dialog.
Is there a way to let the filetype be checked even for newly uploaded files? If it's not possible to prevent the upload, it would be enough to prevent it to be attached / selected after the upload, if the file is not of an allowed type.