Tutorial for custom buttons is already updated:
https://planet-cnc.com/adding-user-t...-tng-software/
Note that instead of "cmd('Machine.Start_Code', 'M900')" you can use simpler "startcode('M900')" command.
Tutorial for custom tabs is here:
https://planet-cnc.com/create-custom...-tng-software/
List of all parameters is in user manual (in know that only list is not enough but it is more that nothing).
Transparent .png should work. You can send file to me and I'll check what is wrong.