@Override
	protected void programActivated(Program program) {
		program.addListener(this);
	}
We need to be aware of changes to the program that could result in scalars being
added/removed. When this happens we want to update the appropriate providers.

@param ev the domain change event
Ghidra/Features/Base/src/main/java/ghidra/app/plugin/core/scalartable/ScalarSearchPlugin.java