FileWatcher
A helper class to simplify WatchService, by creating a (private) background thread, which polls the WatchService, and forwards the messages to created and deleted on the glok thread.
Designed to work with PlacesDock, so that the view remains current when files are created/deleted for any expanded folders in the TreeView.
Typical Usage
Create a concrete subclass, implementing created and deleted. Watch folders using watch and later stop watching it using unwatch.
close ends the background thread, which polls for changes.