Checkbox inside a balloon in KML

I have made a KML program with several placemarks each one with a balloon. Inside each balloon some parameters are displayed. These are shown by means of the element "ExtendedData".The program gives something like this for one single placemark:

![ExtendedData balloon] http://ift.tt/1TEcwk7

I would like to program the balloon so that a checkbox appears before every single parameter. By this way I could hid one parameter if I think is useless.

How could I put a checkbox inside a balloon? I could not find any example