libreoffice has gtk4 support since some time. Please add it in the ebuilds. gtk4 in IUSE additional dependency: gui-libs/gtk[X] $(use_enable gtk4 gtk4) Since about one year I don't have related build errors with enabled gtk4 (using libreoffice-9999). Should be useable with all libreoffice ebuilds in Gentoo. Next big thing will be --enable-qt6 at least when the kde ebuilds are ready for qt6.
A week ago the qt6 flag was added to 24.2 and 9999 ebuilds. So it would be great to have parity and see the gtk4 flag enabled.
Created attachment 885660 [details, diff] gtk4 patch for libreoffice-9999.ebuild renamed gtk USEflag to gtk3, removed the "+" configure.ac says "introspection" needs gtk3 enabled, so not for gtk4? You can see what vclplugin is used in Help>about Use for example "SAL_USE_VCLPLUGIN=gtk4 lowriter" to start with another. If libreoffice is built without gtk,kde,qt vclplugins then it starts with the "gen" backend for x11. We still need the ICU_74.1.patch for the live ebuild to compile.
