EXT Confirm CodeBehind

public void MyFunction()
{
    X.Msg.Confirm("Message", "It'OK??", new MessageBoxButtonsConfig
    {
        Yes = new MessageBoxButtonConfig
        {
            Handler = "CompanyX.It_s_OK()",
            Text = "OK"
        },
        No = new MessageBoxButtonConfig
        {
            Handler = "CompanyX.It_s_KO()",
            Text = "KO"
        }
    }).Show();
}

[DirectMethod(Namespace = "CompanyX")]
public void It_s_OK()
{
    //your OK function
}

[DirectMethod(Namespace = "CompanyX")]
public void It_s_KO()
{
    //your KO function
}