Between Qt 3 and Qt 4 some properties have changed name, some have changed meanings, some have been removed, some are totally new, etc. Some classes (like QTextEdit
and QTextBrowser
) have a completely different API.
However, you can find some correspondences and a lot of notes here: http://qt-project.org/doc/qt-4.8/porting4.html
I've ported some code from Qt 3 to Qt 4, but not to Q t5.