They didn't rewrite the whole software, that would take ages... The migration from C to C++ was slowly progressing since Inkscape was forked from Sodipodi over

They didn't rewrite the whole software, that would take ages... The migration from C to C++ was slowly progressing since Inkscape was forked from Sodipodi over 10 years ago, but there are still some C files remaining and SP* prefixes are used all over the place. Besides, Sodipodi was already using simple GObject-based architecture.