title: C# MS Equation Editor richtextbox issue
body: <p>I have an issue with C# richtextbox and Microsoft equation editor. My goal is to read, modify and save changes in rtf file.
  I followed tutorial below: </p>
  
  <p><a href="https://www.youtube.com/watch?v=j7vRyx0ShVE" rel="nofollow noreferrer">C# Tutorial : How to insert Math Equation to RichTextBox | FoxLearn</a></p>
  
  <p>I can read and modify equation in editor, however I can't update richtextbox after modification, modified value is not changed in richtboxtext.</p>
  
  <p><a href="https://i.stack.imgur.com/6qCMD.png" rel="nofollow noreferrer">Initial state</a></p>
  
  <p><a href="https://i.stack.imgur.com/qxkvq.png" rel="nofollow noreferrer">Modification</a></p>
  
  <p>Update(F3) and exit in equation editor doesn't cause change in richtextbox.
  However when I double click equation in editor there is changed value.</p>
  
  <p>Here is my code:</p>
  
  <pre><code>using System;
  using System.Windows.Forms;
  
  namespace Panel.Views
  {
      public partial class Axis : Form
      {
          public Axis()
          {
              InitializeComponent();
          }
  
          private void button1_Click(object sender, EventArgs e)
          {
              richTextBox1.SelectedRtf = Panel.Properties.Resources.Plot1_x_axis;
          }
      }
  }
  
  
  namespace Panel.Views
  {
      partial class Axis
      {
          /// &lt;summary&gt;
          /// Required designer variable.
          /// &lt;/summary&gt;
          private System.ComponentModel.IContainer components = null;
  
          /// &lt;summary&gt;
          /// Clean up any resources being used.
          /// &lt;/summary&gt;
          /// &lt;param name="disposing"&gt;true if managed resources should be disposed; otherwise, false.&lt;/param&gt;
          protected override void Dispose(bool disposing)
          {
              if (disposing &amp;&amp; (components != null))
              {
                  components.Dispose();
              }
              base.Dispose(disposing);
          }
  
          #region Windows Form Designer generated code
  
          /// &lt;summary&gt;
          /// Required method for Designer support - do not modify
          /// the contents of this method with the code editor.
          /// &lt;/summary&gt;
          private void InitializeComponent()
          {
              this.button1 = new System.Windows.Forms.Button();
              this.richTextBox1 = new System.Windows.Forms.RichTextBox();
              this.SuspendLayout();
              // 
              // button1
              // 
              this.button1.Location = new System.Drawing.Point(723, 431);
              this.button1.Name = "button1";
              this.button1.Size = new System.Drawing.Size(75, 23);
              this.button1.TabIndex = 0;
              this.button1.Text = "button1";
              this.button1.UseVisualStyleBackColor = true;
              this.button1.Click += new System.EventHandler(this.button1_Click);
              // 
              // richTextBox1
              // 
              this.richTextBox1.Location = new System.Drawing.Point(28, 36);
              this.richTextBox1.Name = "richTextBox1";
              this.richTextBox1.Size = new System.Drawing.Size(770, 372);
              this.richTextBox1.TabIndex = 1;
              this.richTextBox1.Text = "";
              // 
              // Axis
              // 
              this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
              this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
              this.ClientSize = new System.Drawing.Size(822, 478);
              this.Controls.Add(this.richTextBox1);
              this.Controls.Add(this.button1);
              this.Name = "Axis";
              this.Text = "Axis";
              this.ResumeLayout(false);
  
          }
  
          #endregion
  
          private System.Windows.Forms.Button button1;
          private System.Windows.Forms.RichTextBox richTextBox1;
      }
  }
  </code></pre>
  
  <p>I would be appreciated for any help, hints or suggestions how to solve this issue.
  Thank you in advance.</p>