private void startChanged(Address address) {
		if (changing) {
			return;
		}
		if (address != null) {
			model.setNewStartAddress(address);
		}
		else {
			setStatusText("Invalid Address");
			setOkEnabled(false);
		}
	}
Dialog that uses a model to validate the fields for moving a block of memory.
Ghidra/Features/Base/src/main/java/ghidra/app/plugin/core/memory/MoveBlockDialog.java