Advance msgbox to have confirmation hotkey support.
Bind certain callback from btnCode to confirm hotkey.
Default when only one button both confirmation and cancel hotkey bind to the >one< callback. (Like assume its info box with "Ok")
Default when two buttons first is cancel hotkey (as it was before) second is confirmation hotkey. (Like "No", "Yes")
Mapping of the binding is done by passing array of the callback indexes which are then mapped to [0] = cancel, [1] = confirm keys.
relates: #4411