Select a folder, open "Actions" flap->"Edit"->"Edit Folder"->"Cache". Most of the dialog unreadable, due to wrong sizes. Seen on 4:4.5~20100902.1170752-1maemo1.1170522 .
"Fixed" with the KDialog fallback code since yesterday.
Confirmed, version 4:4.5~20101013.1185418-1maemo1.1185177 .