private void btPaste_Click(object sender, EventArgs e) { if (Clipboard.ContainsData("MathNode")) { object data = Clipboard.GetData("MathNode"); if (data != null) { string s = data.ToString(); XmlDocument doc = new XmlDocument(); doc.LoadXml(s); if (doc.DocumentElement != null) { try { Type t = XmlUtil.GetLibTypeAttribute(doc.DocumentElement); MathNode node = mathExpCtrl1.AddMathNode(t); node.Load(doc.DocumentElement); mathExpCtrl1.RefreshVariableMap(); mathExpCtrl1.Refresh(); mathExpCtrl1.Focus(); } catch (Exception err) { MessageBox.Show(err.Message); } } } } }