This MT4 installation seems to have some encoding problems. It's destroying the non-ASCII characters. I'm not suspecting the database and also not the web server, but I don't know... Let's see first some screen shots.
Writing new Entry
after clicking "Preview"(note the "You are previewing the entry titled" on top compared to the title in the preview)
after just clicking "Re-Edit this Entry" and again "Preview"
So it seems that the characters comes properly to the code and are properly written to the preview file, but then when used back again for MT4 administration interface, gets messed up.
Little more investigation and it looks like that the FastCGI is doing the double encoding. When using just CGI versions everything works just fine and I can write (šžčťľúüô) what ever I like...