Replaced #else with #elif !HAVE_GTK3 anywhere the legacy alignment calls appear, so the GTK2/legacy path is now explicitly scoped to non-GTK3 builds while preserving the existing GTK3 halign/valign behavior across the requested files (maingui.c, chanlist.c, dccgui.c, joind.c, servlistgui.c).

Applied the same explicit !HAVE_GTK3 guard style in setup.c, including the gtk_alignment_* block and the padding/margin section you called out.

src/fe-gtk/chanlist.c

@@ -89,7 +89,7 @@ chanlist_set_label_alignment (GtkWidget *widget)
 #if HAVE_GTK3
 	gtk_widget_set_halign (widget, GTK_ALIGN_START);
 	gtk_widget_set_valign (widget, GTK_ALIGN_CENTER);
-#else
+#elif !HAVE_GTK3
 	gtk_misc_set_alignment (GTK_MISC (widget), 0, 0.5);
 #endif
 }