LibreWolf is based on Firefox, so it uses QT.
Is Gtk3 , thanksYou can find out with ldd(1):
Code:% ldd /usr/local/lib/firefox/libxul.so | grep gtk libgtk-3.so.0 => /usr/local/lib/libgtk-3.so.0 (0x1414e8200000)
Just need to find the "main" binary or so file to query.