If file-name consists of UTF-8 characters browser try to save an attachment file with non readable name. To prevent such a behavior we must rightly encode file name in header. But the problem is - Microsoft.
We need first to check that browser is not IE and than encode file name according to http://tools.ietf.org/html/rfc2231 (see also http://greenbytes.de/tech/webdav/draft-reschke-rfc2231-in-http-latest.html#RFC2231\)
If client use IE we must simply encode file name in "percent" format (but space we must replace as %20 not + sign)
The second file in patch is a BasePage.html - simply set up UTF-8 encoding in meta tag on the top of all pages - this remove most of the encoding problems.