@Override
	public ProgramSelection getSelection() {
		if (currentProgramSelection == null || currentProgramSelection.isEmpty()) {
			return null;
		}

		FGData currentData = controller.getFunctionGraphData();
		if (!currentData.hasResults()) {
			return null;
		}

		// we want to limit the selections we return here to that which is inside of our
		// graph (the current selection of this provider is that for the entire program)
		Function function = currentData.getFunction();
		AddressSetView functionBody = function.getBody();
		AddressSet intersection = currentProgramSelection.intersect(functionBody);
		return new ProgramSelection(intersection);
	}
Returns true when something destructive has happened to the data upon which the graph has
created, like a memory block move.
Ghidra/Features/FunctionGraph/src/main/java/ghidra/app/plugin/core/functiongraph/FGProvider.java