QML on the desktop is highly buggy. The menu bar doesn't close when you click on other windows (even after 10 years), it took a decade to create a half-decent Qt Quick Controls 2 file dialog, there were multiple tab order bugs where pressing Tab hung the app (in Qt Widgets it would instead highlight the wrong widget when you pressed Tab then Shift-Tab) and one of them was fixed after several years mere weeks ago (https://bugreports.qt.io/browse/QTBUG-87190), mouse scrolling (Flickable) works differently from Widgets (and scrolling twice quickly can travel 4 times the distance as scrolling once), on Android it drops frames even on a fairly high-end phone (Pixel 4a) and interactions feels uncanny-valley... I'm under the impression that you're almost not meant to use Qt Quick Controls 2, since KDE created their own Item hierarchy, rejecting Qt's own Flickable altogether.