Registers a listener that fires whenever the keyboard input source changes.
The listener is called with no arguments. Read currentLayout(), currentSourceID(),
or map inside the callback to inspect the new state.
The OS subscription starts lazily on the first listener and is released automatically
when the last listener is removed via removeWatcher.
Registers a listener that fires whenever the keyboard input source changes. The listener is called with no arguments. Read
currentLayout(),currentSourceID(), ormapinside the callback to inspect the new state. The OS subscription starts lazily on the first listener and is released automatically when the last listener is removed viaremoveWatcher.