I am using KDE4.3RC2 from KDE factory repository, and libqt is from the same repo too.
However, in a Qt application, as long as I input Chinese, text copy and paste in that application failed to work. Here are the ouputs from terminal:
QClipboard::setData: Cannot set X11 selection owner for PRIMARY
QClipboard::setData: Cannot set X11 selection owner for CLIPBOARD
The abovemetioned problem appears in program using qt4.5.2 such as kmess, kopete, kile, qstardict, and there is also a similar bug report in Gentoo community:
Gentoo Bug 276527 - Qt 4.5.2 applications cannot copy text after input some Chinese