From FCKeditor Docs

GetFolders

Gets the list of the children folders of a folder.

Sample Request

Get child folders from the /Docs/ folder of the resource type “Images”.

connector.php?command=GetFolders&type=Images&currentFolder=%2FDocs%2F

Sample Response

<?xml version="1.0" encoding="utf-8"?>
<Connector resourceType="Images">
 <Error number="0" />
 <CurrentFolder path="/" url="/userfiles/images/Docs/" acl="255" />
 <Folders>
 <Folder name="Earth" hasChildren="false" acl="255" />
 <Folder name="Flowers" hasChildren="false" acl="255" />
 <Folder name="Moon" hasChildren="true" acl="255" />
 <Folder name="繁體中文字" hasChildren="false" acl="255" />
 </Folders>
</Connector>

Note that the folder names may contain non ASC-II chars, like the following example with Chinese characters.