in MDL-33419 it was noted that the filepicker icons list is hardcoded with fp-reficons1 and fp-reficons2 and so on..

it was noted here (http://tracker.moodle.org/browse/MDL-33419?focusedCommentId=165448&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-165448) that we can change this now to be a proper list with icons being added into the list.