qt4 applications don't work in Xephyr

I am using Xephyr to run applications as another user, while being logged in as primary user. Most applications work fine in Xephyr, except qt4 based. Specifically: electrum ipython qtconsole qbittorrent The above applications work when started in normal X server, but when I start them in Xephyr, I only see the window frame, but it is blank. How can I fix this problem ? My OS is Debian Wheezy and version numbers are: xserver-xephyr 1.12.4 libqtcore4 4.8.2 Here is how I start my Xephyr session: Xephyr :1 -screen 1920x1080 -nolisten tcp -reset -terminate >/dev/null 2>&1 & terminator --execute su - user2 -c 'DISPLAY=:1 startlxde >/dev/null 2>&1 &' **UPDATE** I have tested with XFCE4 and have the same problem. QT4 applications still don't work, I get a blank window. As example, see how qbittorrent window loks like: