From QEglFSWindow::create()
@
#if !defined(Q_OS_ANDROID) || defined(Q_OS_ANDROID_NO_SDK)
// We can have either a single OpenGL window or multiple raster windows.
// Other combinations cannot work.
qFatal("EGLFS: OpenGL windows cannot be mixed with others.");
@
Details can be found at https://qt.gitorious.org/qt/qtbase/commit/f89f099c55576992b39a8021aace64ff32747624/
edit: I did not notice that this is in the Japanese forum.