Qt Designer[0] (for widget-based interfaces) is still a thing, and they have added Qt Quick[1] and Qt Quick Controls (for QML-based interfaces). Recently they’

Qt Designer[0] (for widget-based interfaces) is still a thing, and they have added Qt Quick[1] and Qt Quick Controls (for QML-based interfaces). Recently they’ve been integrated into the IDE but with a right click on a file (within the IDE file browser or project browser panes) you can open a .ui file in the external Designer. [0]: https://doc.qt.io/qt-5/qtdesigner-manual.html https://doc.qt.io/qt-5/qtdesigner-manual.html [1]: https://doc.qt.io/qt-5/qtquick-index.html https://doc.qt.io/qt-5/qtquick-index.html