Replaced the GTK3 G_DECLARE_DERIVABLE_TYPE usage with explicit GtkXText typedefs/macros to keep the instance struct visible in GTK3 builds and avoid missing member errors.
Switched GtkXText and CustomList implementations to G_DEFINE_TYPE/G_DEFINE_TYPE_WITH_CODE and preserved parent chaining behavior
Added GTK3/GTK2 conditional type declarations for GtkXText while restoring the legacy macro block for GTK2 builds.
Restored GTK2-friendly typedefs/macros and parent field naming for CustomList alongside GTK3 G_DECLARE_DERIVABLE_TYPE usage.
Restored GTK2-friendly typedefs/macros and parent field naming for SexySpellEntry while keeping GTK3 declarations intact.
Restored legacy RemoteObject typedefs and GType macros in the D-Bus plugin to keep GTK2 builds from seeing incomplete types or missing fields/macros.