I’m not aware of any good documentation. The button can do all kind of actions. This includes opening some main forms and do all kind of keyboard simulations.
The list of options as Command is very large. Are you looking for a particular command or task to do?
The operation specified in the properties of the button is invoked. It is kernel implemented, so you won’t be able to see the code behind
on OK the closeOK would be called on the form. on Cancel - closeCancel, etc.