static public void Transform (Brush b)
{
Assert.IsNotNull (b.Transform, "Transform");
MatrixTransform mt = (b.Transform as MatrixTransform);
Matrix m = mt.Matrix;
m.M11 = 2.0;
Assert.IsTrue (mt.Matrix.IsIdentity, "OldCopy/Identity");
b.Transform = null;
Assert.IsNotNull (b.Transform, "Transform/NeverNull");
Assert.IsTrue ((b.Transform as MatrixTransform).Matrix.IsIdentity, "Transform/Null/Identity");
b.SetValue (Brush.TransformProperty, null);
Assert.IsNotNull (b.Transform, "Transform/NeverNullDP");
}