private static TextParam getFunctionGroupDisplayString(final FormulaFunction.FunctionGroup g) {
        return
            TextParam.text("**" + (g == null ? "null" : g.getUserDisplayableString()) + "**").setMarkdown(true);
    }
Shows a function selection dialog, and upon user selection pastes the function into the formula field given by 'formulaView'
main/src/main/java/cgeo/geocaching/utils/formulas/FormulaUtils.java