@Override
		public String toString() {
			//@formatter:off
			return "{\n" +
				"\twasShown: " + wasShown + "\n" +
				"\ttext: "  + text + "\n" + 
				"\ttrace: " + ReflectionUtilities.stackTraceToString(source)+ "\n" +
			"}";
			//@formatter:on
		}
A spy that tracks window shown and hidden events from the {@link DropDownSelectionTextField}.

<P>Synchronization Policy: the event storage of this class is synchronized to prevent 
concurrent modification exceptions between reading and writing.
Ghidra/Framework/Docking/src/test/java/docking/widgets/SpyDropDownWindowVisibilityListener.java