Attached is a minimal app created with Qt 5.2.1. If you try to start this using Qt 5.3.0 snapshot it won't work. The code will hang somewhere inside QtQuick2ApplicationViewer::setMainQmlFile(). There are no error messages.

// main.cpp
QtQuick2ApplicationViewer viewer;
qDebug() << "### Before";
viewer.setMainQmlFile(QStringLiteral("qml/test22/main.qml"));
// Next line is never called
qDebug() << "### After";

It looks like it has something to do with loading QML components from assets. If you remove the ScaledText element from main.qml the app will start up normally.

Tested with latest snapshot: http://mirror.netcologne.de/qtproject/snapshots/qt/5.3/5.3.0-beta/2014-03-20_20/qt-opensource-linux-x64-android-5.3.0-beta_2014-03-20_10-01-06-20.run