xubuntu – Running GTK applications in XFCE as if in MATE

On 24.04, when running, for example, thunar in XFCE 4.18 it seems to be using a different version of GTK than when run in MATE 1.26. A difference is that MATE 1.26 still displays the Alt-key mnemonics (menu accelerators/access keys, the underlined letters in the window menus), while in XFCE 4.18 this feature is gone because it was deprecated in GTK3. Even non-XFCE applications, like gimp, have the mneomics in MATE 1.26 but no longer in XFCE 4.18.

Is it possible to run applications in XFCE (e.g. maybe with some LD_PRELOAD or LD_LIBRARY_PATH) so that they run as if in MATE?

What accounts for this difference between XFCE 4.18 and MATE 1.26? They both use GTK3.