@elextr Are you sure that’s necessary?
No. But but it certainly didn't work at some point in the past, hence the workaround in the first place :)
But maybe GTK has "standardised" on an undocumented behaviour of [gtk_menu_item_set_label()](https://developer.gnome.org/gtk3/stable/GtkMenuItem.html#gtk-menu-item-set-l...) not changing the mnemonic setting on the underlying label despite normal [gtk_label_set_text()](https://developer.gnome.org/gtk3/stable/GtkLabel.html#gtk-label-set-text) explicitly clearing the flag.
GTK experts shall have to pronounce.