Trying to generate a simple printable form, I have encountered the following problem: I need a square button with two alphabetic characters, which can either be made visible / invisible or highlighted on mouse click. Is it possible to modify a checkbox by using a certain script, so that the checkmark or cross changes into two alphabetic characters? Another option would be to create an image button which shows the two characters and make it visible / invisible on mouse click, so that the background graphics will be alternately visible. Further actions are not required. Thanks in advance for an easy-to-understand solution.