protected boolean isValidAddress(Address addr) {
		if (addr == null || program == null) {
			return false;
		}
		return program.getMemory().contains(addr) || addr.isExternalAddress();
	}
{@link GraphDisplayListener} that handles events back and from program graphs.
Ghidra/Features/ProgramGraph/src/main/java/ghidra/graph/program/BlockModelGraphDisplayListener.java