Crop & Aspect Ratio Icons This is a very loosely associated question but looking at the plugin page for Pimp My Matrix, they depict icons for Crop Position, and Crop Aspect Ratio:



Are these custom fields from somewhere or is it possible somehow to add your own icons for something which looks to be essentially a radio button or select type of field?
This looks like the Button Box plugin, also from the team who developed Pimp My Matrix.