this.Listener.ThumbnailButtons.Configure(c =>
{
    c.AddButton()
        .For(this.Handle)
        .WithId(1)
        .WithToolTip("First button")
        .UseIcon(SystemIcons.Asterisk)
        .UseCallback(b => MessageBox.Show("You clicked a button with name: " + b.ToolTip));
 
    c.AddButton()
        .For(this.Handle)
        .WithId(2)
        .WithToolTip("Second Button")
        .UseIcon(SystemIcons.Error); 
});