I can't add files with Cyrillic names. --- Xfce 4.4.0, 2.6.18-gentoo-r4
Thank you for your bug report. Could you please try if this is fixed in svn?
This seem to be fixed in trunk, i created an empty text file named опрстуфх цчш (grabbed those caracters on wikipedia), and could add it without any issues to a composition.
Thank you for testing. Resolving as fixed.