private JPanel buildSignaturePanel() {
		JPanel signaturePanel = new JPanel();
		signaturePanel.setLayout(new BoxLayout(signaturePanel, BoxLayout.X_AXIS));

		signatureField = new JTextField(SIGNATURE_COLUMNS);
		signatureLabel = new GDLabel("Signature:");
		signaturePanel.add(signatureLabel);
		signaturePanel.add(signatureField);

		signaturePanel.setBorder(BorderFactory.createEmptyBorder(5, 5, 5, 5));

		signaturePanel.getAccessibleContext().setAccessibleName("Signature");

		return signaturePanel;
	}
Method must be invoked following construction to fetch function info 
and update components.
Ghidra/Features/Base/src/main/java/ghidra/app/plugin/core/function/AbstractEditFunctionSignatureDialog.java