static bool IsDrag(IList<DragPoint> dragSeq)
{
Point<float> first = dragSeq[0].Point;
Size ds = SystemInformation.DragSize;
return dragSeq.Any(p =>
{
var delta = p.Point.Sub(first);
return Math.Abs(delta.X) > ds.Width || Math.Abs(delta.Y) > ds.Height;
});
}