Comment by mnafees

I wrote Qt C++ for 7 years as an open source contributor to KDE. This reminds me of QtWidgets’ .ui files—custom XML files following a specific schema. Later, Qt introduced QML, which I personally found unintuitive, and over time I lost interest in Qt altogether. That said, I still think XML for UI definitions makes sense, and it’s understandable that some larger environments continue to use it.