The xxkb program is a keyboard layout switcher and indicator.  Unlike the
programs that reload keyboard maps and use their own hot-keys, xxkb is a
simple GUI for XKB (X keyboard extension) and just sends commands to and
accepts events from XKB.  That means that it will work with the existing
configuration of X11 server without any modifications.

Additional features include:

  - Remembers the current layout in each application and switches to it
    on window focus change
  - Can put its own icon on an application window titlebar
  - Allows to designate two main layouts from multi-layout keymaps
  - Alternative layouts can be set separately for each application and
    can be changed during run-time
  - Supports custom actions for certain windows (e.g. ignore, set initial
    active layout on application startup)
  - Can be docked as a docklet or placed in the system tray

WWW: https://sourceforge.net/projects/xxkb/