Removed GTK2 compatibility shims from headers (fe-gtk.h, gtkutil.h), leaving direct GTK3-facing declarations/includes only (and platform-specific guards unrelated to GTK2 kept as-is).
Cleaned GTK2-specific comments/wording now that behavior is GTK3-native (menu accelerator note and emoji/userlist comment blocks).
Guarded tree view palette application to use GTK3 font descriptions or GTK2 styles appropriately.
Adjusted the chanview creation call site to pass GTK3 font descriptions or GTK2 styles based on the build.