public void DeleteSelectedKey()
{
LinkedListNode<CurvePoint> point = SelectedCurve.CurvePoints.Find(SelectedPoint);
if (point != null)
{
if (point.Previous != null)
{
SelectedPoint = point.Previous.Value;
}
else if (point.Next != null)
{
SelectedPoint = point.Next.Value;
}
SelectedCurve.RemovePoint(point);
Paint();
}
}