Font hinting is disabled on multi-screen KDE systems

By default, KDE sets the QT_SCREEN_SCALE_FACTORS, which causes Qt to call QHighDpiScaling::setScreenFactor(), which unconditionally sets m_active=true, turning off font hinting.

The fix is to make QHighDpiScaling::setScreenFactor() only set m_active when actually scaling:

if (!qFuzzyCompare(factor, qreal(1)) m_active=true;