@Override
	public String getTooltipText(FcgVertex v, MouseEvent e) {
		// TODO we could have the name label return just the function name; the vertex shape
		//      return a full function signature and the +/- toggle buttons return a tip

		Component child = e.getComponent();

		// the buttons may have extra information
		if (child instanceof JButton) {
			return ((JButton) child).getToolTipText();
		}

		return v.getName();
	}
A class that provides tooltips for a given vertex
Ghidra/Features/GraphFunctionCalls/src/main/java/functioncalls/graph/renderer/FcgTooltipProvider.java