gxkb is a little indicator applet which allows one to quickly switch
between different keyboard layouts in X11.  A flag corresponding to
the country of the active layout is shown in the system tray area.

The applet is written in C and uses GTK+ 2.0 library (and therefore
does not depend on any GNOME components) and can maintain separate
per-window, per-application, or global layout states.

WWW: https://zen-tools.github.io/gxkb/