private Component buildInitializedRadioButtonPanel() {
		JPanel panel = new JPanel(new HorizontalLayout(10));

		ButtonGroup radioGroup = new ButtonGroup();
		initializedRB = new GRadioButton("Initialized", false);
		initializedRB.setName(initializedRB.getText());
		initializedRB.addActionListener(ev -> initializeRBChanged());

		initializedFromFileBytesRB = new GRadioButton("File Bytes", false);
		initializedFromFileBytesRB.setName(initializedRB.getText());
		initializedFromFileBytesRB.addActionListener(ev -> initializeRBChanged());

		uninitializedRB = new GRadioButton("Uninitialized", true);
		uninitializedRB.setName(uninitializedRB.getText());
		uninitializedRB.addActionListener(ev -> initializeRBChanged());

		radioGroup.add(initializedRB);
		radioGroup.add(initializedFromFileBytesRB);
		radioGroup.add(uninitializedRB);

		panel.add(initializedRB);
		panel.add(initializedFromFileBytesRB);
		panel.add(uninitializedRB);

		return panel;
	}
Define the Main panel for the dialog here.
Ghidra/Features/Base/src/main/java/ghidra/app/plugin/core/memory/AddBlockDialog.java