protected override void OnPaint(PaintEventArgs e)
{
if (_labelVisible && root != null)
{
MathNode mv = var as MathNode;
if (mv != null)
{
SizeF s = mv.CalculateDrawSize(e.Graphics);
this.Size = new Size((int)s.Width, (int)s.Height);
mv.Draw(e.Graphics);
}
}
}