either you can make a calculated media field that you can use as button...
switchfield, number, global or not global depending on your needs
(this is set either to 1 or 0)
imagefieldselected, media, global
imagefieldunselected, media, global
mybuttonfield, calculated, media, if (switchfield =1; imagefieldselected; imagefieldunselected)
so you can switch between two different images (or an empty image) for your button.
or you can use the example Feld sichtbar / unsichtbar. If you like the example, make a donation to a wellfare organisation of your choice, and make a proof-entry to my database.
greetings from germany