[solved] Qt writes to /dev/tty0

[incogn1to]

Qt opens /dev/tty0 with echo enabled. As a result keystrokes are visible on screen buffer.
@stty -F /dev/tty0 -echo @

Solves the problem until application restart. Is there a way to force Qt to open /dev/tty0 with echo disabled? Or to disable console output stream to screen buffer? I found this topic with similar problem: http://qt-project.org/forums/viewthread/4778 but compiling QT with -qt-kbd-tty doesn't solve the problem.
Any suggestions?
Qt: 4.8.1
Embeded Linux system

[upd]
Even if I setup “QWS_KEYBOARD” environment to “TTY:/dev/null” – keyboard stops working but echo is still active and visible on screen.

[incogn1to]

Even if I setup "QWS_KEYBOARD" environment to "TTY:/dev/null" - keyboard stops working but echo is still active and visible on screen.

[incogn1to]

Solution: Can be done by setting environment QWS_DISPLAY to "LinuxFb:tty=/dev/null"