public void Filter ()
{
ItemCollection c = new ItemsControl ().Items;
c.Add (1);
c.Add (-1);
Assert.AreEqual (c.Count, 2, "1");
c.Filter = FilterFilter;
Assert.AreEqual (c.Count, 1, "2");
c.Filter = null;
Assert.AreEqual (c.Count, 2, "3");
c.Filter = FilterFilter;
c.Add (2);
Assert.AreEqual (c.Count, 2, "4");
c.Filter = null;
Assert.AreEqual (c.Count, 3, "5");
c.Filter = FilterFilter;
c.Remove (-1);
c.Filter = null;
Assert.AreEqual (c.Count, 2, "6");
}
