These features do not have the compatibility against the current IBus

• Delete deprecated DBus methods
• Delete deprecated IBus, GTK, GLib APIs
• Delete InputContext.SetEngine
• DONE Delete gconf, support GSettings key names only, implement more GVariant formats in GSettings value instead of GSettingsList. See also GSettingsMigration
• Move /desktop/ibus path to /org/freedesktop/ibus path for glib-compile-schemas
• Improve ibus_input_context_set_cursor_location() for multiple monitors besides multiple screens for ZaphodHeads mode
• Use gtk_widget_set_margin_start|end() instead of set_margin_left|right
• Delete g_type_init
• DONE Delete Super-space notification
• Delete IBusXEvent
• EngineProxy sends the object name in FocusIn to remember the input mode and client name in FocusIn to distinguish gtk2/gtk3/gtk4
• Wayland colors
• Delete GSettings key org.freedesktop.ibus.general.hotkey.trigger but not triggers