If I switch to cyrillic keyboard layout copy/past operations with CTRL+C, CRTL+V stop works in any QT widgets (e.g. QTextEdit). The problem is reproduced in my QT application, QT-Creator 3.3.0, QT Designer 5.4. To reproduse it:
1. Launch QT Designer 5.4
2. Create new Dialog
3. Add QTextEdit to Dialog
4. Press CTRL+R to execute dialog preview.
5. Print some text in text edit box.
6. Try to copy and past your text with CTRL+C & CTRL+V shortcuts.
7. Switch the keyboard layout to cyrillic language (Russian in my case).
8. Repeat operation 6 copy and past your text with CTRL+C & CTRL+V shortcuts.
Expectes that operation 8 copy and past text properly.
Realy CTRL+C & CTRL+V do nothing.