When you highlight some songs, the highlight exceeds its pane. The problem appears when ReadTags is set and also when it isn't. It's probably caused by some encoding problem because there is no sign of bad behaviour when playing english spelled files. You can see it here: http://zp.emdej.com/~mdj/moc24/
This is probably something that can be fixed by adding librcc/librcd (http://rusxmms.sourceforge.net/) to portage and adding a USE flag for it. I don't have any tag files that use alternative charsets, so I don't really have any way to test/maintain the libs, we need to find a dev willing to maintain these packages so they can be added to portage.
try this one: http://zp.emdej.com/~mdj/moc24/sample.mp3
MOC developer now knows about the bug: "Thanks, I know about this problem. It does not occur if you are using UTF-8 locales. -- Damian Pietras - MOC developer"
This problem has to be fixed upstream.