public void ChildControlsOfType()
{
var userControl = new UserControl {ID = "uc"};
var panel = new Panel {ID = "pl"};
var htmlUl = new HtmlGenericControl("ul") {ID = "ul"};
var htmlLi = new HtmlGenericControl("li") {ID = "li"};
htmlLi.Controls.Add(new CheckBox {ID = "ckb1"});
htmlUl.Controls.Add(htmlLi);
panel.Controls.Add(htmlUl);
panel.Controls.Add(new CheckBox {ID = "ckb2"});
userControl.Controls.Add(panel);
var checkBoxes = userControl.Controls<CheckBox>();
Assert.AreEqual(2, checkBoxes.Count());
Console.Write("Found: ");
checkBoxes.ToList().ForEach(ckb => Console.Write(ckb.ID + ", "));
}