Classic User interface
This is a simple theme engine based on Fcitx 5's own ini-like configuration file and images. This affect the server side input method panel and Fcitx 5's new client side input method panel. Under X11, the input method window is rendered by Fcitx server. But under wayland, it might be rendered by the client application for Gtk and Qt. They share similar logic and almost same features. Except in Qt case, it is rendered with native Qt API, so it does not support the "Use input method language to display text" option.