Found a way to make Form buttons close!!

```bash
#!/bin/bash

function choice(){
    echo $1
    kill -s SIGTERM $YAD_PID
}
export -f choice

yad --form --text="Choose a browser to launch:" \
    --field="Foo":fbtn "bash -c 'choice hello'" \
    --field="bar":fbtn "bash -c 'choice world'" \
    --button=gtk-cancel:1
exit
```
discovered here: https://sourceforge.net/p/yad-dialog/tickets/211/