Qt5 to Qt4 UI File Compatibility

Question

Are Qt5 generated UI/form files backwards compatible with Qt4? As in, can I take the source, headers, and UI files and recompile with Qt4 without issue?

Answer 1

The files generated by uic in Qt 5 will have #include <QtWidgets/QFoo>, which of course doesn't work in Qt 4.

Or are you talking about .ui files generated by Qt Designer / Creator? Those will instead work without changes (modulo using Qt 5-only or Qt 4-only classes, of course).