After this commit [1] in Qt, QAbstractEventDispatcher::instance()->metaObject()->className() returns "QXcbGlibEventDispatcher", so the glib event loop test fails
[1] http://code.qt.io/cgit/qt/qtbase.git/commit/?h=5.12&id=80b1cce0cfe5d8e527731b921fd5d0c1a007afd5