extension manifest, and use the "file_browser_handlers" { "name": "Upload to flickr", ... "file_browser_handlers": [ { "id": "upload", "default_title": "Save to flickr", // What the button will display "file_filters": [ "filesystem:*.jpg", "filesystem:*. jpeg", "filesystem:*.png" ] } ], "permissions" : [ "fileBrowserHandler" ], "icons": { "16": "icon16.png", "48": "icon48.png", "128": "icon128.png" } }