void TextBox1_Leave (object sender, EventArgs e)
{
Assert.IsFalse (_textBox1.Focused, "#A1");
Assert.IsTrue (_textBox2.Focused, "#A2");
Controls.Remove (_textBox2);
Assert.IsTrue (_textBox1.Focused, "#B1");
Assert.IsFalse (_textBox2.Focused, "#B2");
Close ();
}