REG: Can't switch input language under Linux

Basic application like Qt Text Editor from examples (http://qt-project.org/doc/qt-5/gettingstartedqt.html)
In Linux, if input language changed from English to Russian (I believe it will also reproducible with other languages) the QKeyEvent->key() still contains English language. If application started with Russian language selected in system, than after switching to English the language remains Russian.
I have checked other versions, and in Qt 5.0.2 this works well (language switched properly), in all latest versions the bug is reproducible.