Douglas Alder of Homebase software puts the button bar through it's paces and delivers a great looking, easy to build, reusable on multiple layouts with only one script, Alphabetical Search Button Bar:
FileMaker Pro 14’s new button bar brings a new twist to an old technique for creating alphabetic searches of your data. Instead of creating 26 individual buttons it is possible to create a single button bar object and then easily reformat it using text style changes or FileMaker CSS style changes. The button bar can also be repurposed to horizontal or vertical layouts. Finally I demonstrate how to use the same script from different contexts to perform different searches — a list search and a portal filter.
Since the button bar is one object, applying style changes is easy. And the script he wrote is almost modular, requiring only minor modifications to repurpose it for other layouts.
Check it out and download the example file at the link.