void initLine(Color c)
{
line = new ArrowLine();
line.ArrowAngle = 40;
line.Stroke = new SolidColorBrush(c);
line.StrokeThickness = ShapeUtils.LINE_WIDTH;
line.Effect = ShapeUtils.ShadowProvider();
line.Tag = this;
selMarker1 = ShapeUtils.MakeLinkEnd();
selMarker1.Tag = this;
selMarker2 = ShapeUtils.MakeLinkEnd();
selMarker2.Tag = this;
line.MouseWheel += MouseWheel;
}